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Define your agent

Create a reusable, versioned agent configuration.

An agent is a reusable, versioned configuration that defines persona and capabilities. It bundles the model, system prompt, tools, MCP servers, and skills that shape how Claude behaves during a session.

Create the agent once as a reusable resource and reference it by ID each time you start a session. Agents are versioned and easier to manage across many sessions.

Note

All Managed Agents API requests require the managed-agents-2026-04-01 beta header. The SDK sets the beta header automatically.

Agent configuration fields

FieldDescription
nameRequired. A human-readable name for the agent.
modelRequired. The Claude model that powers the agent. All Claude 4.5 and later models are supported.
systemA system prompt that defines the agent's behavior and persona. The system prompt is distinct from user messages, which should describe the work to be done.
toolsThe tools available to the agent. Combines pre-built agent tools, MCP tools, and custom tools.
mcp_serversMCP servers that provide standardized third-party capabilities.
skillsSkills that supply domain-specific context with progressive disclosure.
multiagentA coordinator declaration listing the agents this agent can delegate to. See Multiagent sessions.
descriptionA description of what the agent does.
metadataArbitrary key-value pairs for your own tracking.

Create an agent

The following example defines a coding agent that uses Claude Opus 4.7 with access to the pre-built agent toolset. The toolset lets the agent write code, read files, search the web, and more. See the agent tools reference for the full list of supported tools.

agent=$(curl -fsSL https://api.anthropic.com/v1/agents \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: managed-agents-2026-04-01" \
  -H "content-type: application/json" \
  -d '{
    "name": "Coding Assistant",
    "model": "claude-opus-4-7",
    "system": "You are a helpful coding agent.",
    "tools": [{"type": "agent_toolset_20260401"}]
  }')

AGENT_ID=$(jq -r '.id' <<< "$agent")
AGENT_VERSION=$(jq -r '.version' <<< "$agent")

ant beta:agents create \
  --name "Coding Assistant" \
  --model '{id: claude-opus-4-7}' \
  --system "You are a helpful coding agent." \
  --tool '{type: agent_toolset_20260401}'

agent = client.beta.agents.create(
    name="Coding Assistant",
    model="claude-opus-4-7",
    system="You are a helpful coding agent.",
    tools=[
        {"type": "agent_toolset_20260401"},
    ],
)

const agent = await client.beta.agents.create({
  name: "Coding Assistant",
  model: "claude-opus-4-7",
  system: "You are a helpful coding agent.",
  tools: [{ type: "agent_toolset_20260401" }],
});

var agent = await client.Beta.Agents.Create(new()
{
    Name = "Coding Assistant",
    Model = new("claude-opus-4-7"),
    System = "You are a helpful coding agent.",
    Tools =
    [
        new BetaManagedAgentsAgentToolset20260401Params
        {
            Type = "agent_toolset_20260401",
        },
    ],
});

agent, err := client.Beta.Agents.New(ctx, anthropic.BetaAgentNewParams{
	Name: "Coding Assistant",
	Model: anthropic.BetaManagedAgentsModelConfigParams{
		ID: "claude-opus-4-7",
	},
	System: anthropic.String("You are a helpful coding agent."),
	Tools: []anthropic.BetaAgentNewParamsToolUnion{{
		OfAgentToolset20260401: &anthropic.BetaManagedAgentsAgentToolset20260401Params{
			Type: anthropic.BetaManagedAgentsAgentToolset20260401ParamsTypeAgentToolset20260401,
		},
	}},
})
if err != nil {
	panic(err)
}

var agent = client.beta().agents().create(
    AgentCreateParams.builder()
        .name("Coding Assistant")
        .model(BetaManagedAgentsModel.CLAUDE_OPUS_4_7)
        .system("You are a helpful coding agent.")
        .addTool(
            BetaManagedAgentsAgentToolset20260401Params.builder()
                .type(BetaManagedAgentsAgentToolset20260401Params.Type.AGENT_TOOLSET_20260401)
                .build()
        )
        .build()
);

$agent = $client->beta->agents->create(
    name: 'Coding Assistant',
    model: 'claude-opus-4-7',
    system: 'You are a helpful coding agent.',
    tools: [
        BetaManagedAgentsAgentToolset20260401Params::with(
            type: 'agent_toolset_20260401',
        ),
    ],
);

agent = client.beta.agents.create(
  name: "Coding Assistant",
  model: "claude-opus-4-7",
  system_: "You are a helpful coding agent.",
  tools: [{type: "agent_toolset_20260401"}]
)
Tip

To use Claude Opus 4.6 or Claude Opus 4.7 with fast mode, pass model as an object: {"id": "claude-opus-4-7", "speed": "fast"}.

The response echoes your configuration and adds id, type, version, created_at, updated_at, and archived_at fields. The version starts at 1 and increments each time an update changes the agent.

{
  "id": "agent_01HqR2k7vXbZ9mNpL3wYcT8f",
  "type": "agent",
  "name": "Coding Assistant",
  "model": {
    "id": "claude-opus-4-7",
    "speed": "standard"
  },
  "system": "You are a helpful coding agent.",
  "description": null,
  "tools": [
    {
      "type": "agent_toolset_20260401",
      "default_config": {
        "permission_policy": { "type": "always_allow" }
      }
    }
  ],
  "skills": [],
  "mcp_servers": [],
  "metadata": {},
  "version": 1,
  "created_at": "2026-04-03T18:24:10.412Z",
  "updated_at": "2026-04-03T18:24:10.412Z",
  "archived_at": null
}

Update an agent

Updating an agent generates a new version when the configuration changes. Pass the current version to ensure you're updating from a known state.

updated_agent=$(curl -fsSL "https://api.anthropic.com/v1/agents/$AGENT_ID" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: managed-agents-2026-04-01" \
  -H "content-type: application/json" \
  -d @- <<EOF
{
  "version": $AGENT_VERSION,
  "system": "You are a helpful coding agent. Always write tests."
}
EOF
)

echo "New version: $(jq -r '.version' <<< "$updated_agent")"

ant beta:agents update \
  --agent-id "$AGENT_ID" \
  --version "$AGENT_VERSION" \
  --system "You are a helpful coding agent. Always write tests."

updated_agent = client.beta.agents.update(
    agent.id,
    version=agent.version,
    system="You are a helpful coding agent. Always write tests.",
)

print(f"New version: {updated_agent.version}")

const updatedAgent = await client.beta.agents.update(agent.id, {
  version: agent.version,
  system: "You are a helpful coding agent. Always write tests.",
});

console.log(`New version: ${updatedAgent.version}`);

var updatedAgent = await client.Beta.Agents.Update(agent.ID, new()
{
    Version = agent.Version,
    System = "You are a helpful coding agent. Always write tests.",
});

Console.WriteLine({{CONTENT}}quot;New version: {updatedAgent.Version}");

updatedAgent, err := client.Beta.Agents.Update(ctx, agent.ID, anthropic.BetaAgentUpdateParams{
	Version: agent.Version,
	System:  anthropic.String("You are a helpful coding agent. Always write tests."),
})
if err != nil {
	panic(err)
}

fmt.Printf("New version: %d\n", updatedAgent.Version)

var updatedAgent = client.beta().agents().update(
    agent.id(),
    AgentUpdateParams.builder()
        .version(agent.version())
        .system("You are a helpful coding agent. Always write tests.")
        .build()
);

IO.println("New version: " + updatedAgent.version());

$updatedAgent = $client->beta->agents->update(
    $agent->id,
    version: $agent->version,
    system: 'You are a helpful coding agent. Always write tests.',
);

echo "New version: {$updatedAgent->version}\n";

updated_agent = client.beta.agents.update(
  agent.id,
  version: agent.version,
  system_: "You are a helpful coding agent. Always write tests."
)

puts "New version: #{updated_agent.version}"

Update semantics

  • Omitted fields are preserved. You only need to include the fields you want to change.

  • Scalar fields (model, system, name, description) are replaced with the new value. system and description can be cleared by passing null. model and name are mandatory and cannot be cleared.

  • Array fields (tools, mcp_servers, skills) are fully replaced by the new array. To clear an array field entirely, pass null or an empty array.

  • multiagent is replaced as a whole, including its agents roster. Pass null to clear it.

  • Metadata is merged at the key level. Keys you provide are added or updated. Keys you omit are preserved. To delete a specific key, set its value to an empty string.

  • No-op detection. If the update produces no change relative to the current version, no new version is created and the existing version is returned.

Agent lifecycle

OperationBehavior
UpdateGenerates a new agent version when the configuration changes.
List versionsReturns the full version history so you can track changes over time.
ArchiveMakes the agent read-only. New sessions cannot reference it, but existing sessions continue to run.

List versions

Fetch the full version history to track how an agent has changed over time.

curl -fsSL "https://api.anthropic.com/v1/agents/$AGENT_ID/versions" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: managed-agents-2026-04-01" \
  | jq -r '.data[] | "Version \(.version): \(.updated_at)"'

ant beta:agents:versions list --agent-id "$AGENT_ID"

for version in client.beta.agents.versions.list(agent.id):
    print(f"Version {version.version}: {version.updated_at.isoformat()}")

for await (const version of client.beta.agents.versions.list(agent.id)) {
  console.log(`Version ${version.version}: ${version.updated_at}`);
}

var versions = await client.Beta.Agents.Versions.List(agent.ID);
await foreach (var version in versions.Paginate())
{
    Console.WriteLine({{CONTENT}}quot;Version {version.Version}: {version.UpdatedAt:O}");
}

iter := client.Beta.Agents.Versions.ListAutoPaging(ctx, agent.ID, anthropic.BetaAgentVersionListParams{})
for iter.Next() {
	version := iter.Current()
	fmt.Printf("Version %d: %s\n", version.Version, version.UpdatedAt.Format(time.RFC3339))
}
if err := iter.Err(); err != nil {
	panic(err)
}

for (var version : client.beta().agents().versions().list(agent.id()).autoPager()) {
    IO.println("Version " + version.version() + ": " + version.updatedAt());
}

foreach ($client->beta->agents->versions->list($agent->id)->pagingEachItem() as $version) {
    echo "Version {$version->version}: {$version->updatedAt->format(DateTimeInterface::ATOM)}\n";
}

client.beta.agents.versions.list(agent.id).auto_paging_each do
  puts "Version #{it.version}: #{it.updated_at.iso8601}"
end

Archive an agent

Archiving makes the agent read-only. Existing sessions continue to run, but new sessions cannot reference the agent. The response sets archived_at to the archive timestamp.

archived=$(curl -fsSL -X POST "https://api.anthropic.com/v1/agents/$AGENT_ID/archive" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: managed-agents-2026-04-01")

echo "Archived at: $(jq -r '.archived_at' <<< "$archived")"

ant beta:agents archive --agent-id "$AGENT_ID"

archived = client.beta.agents.archive(agent.id)

print(f"Archived at: {archived.archived_at.isoformat()}")

const archived = await client.beta.agents.archive(agent.id);
console.log(`Archived at: ${archived.archived_at}`);

var archived = await client.Beta.Agents.Archive(agent.ID);
Console.WriteLine({{CONTENT}}quot;Archived at: {archived.ArchivedAt:O}");

archived, err := client.Beta.Agents.Archive(ctx, agent.ID, anthropic.BetaAgentArchiveParams{})
if err != nil {
	panic(err)
}
fmt.Printf("Archived at: %s\n", archived.ArchivedAt.Format(time.RFC3339))

var archived = client.beta().agents().archive(agent.id());
IO.println("Archived at: " + archived.archivedAt().orElseThrow());

$archived = $client->beta->agents->archive($agent->id);

echo "Archived at: {$archived->archivedAt->format(DateTimeInterface::ATOM)}\n";

archived = client.beta.agents.archive(agent.id)
puts "Archived at: #{archived.archived_at.iso8601}"

Next steps