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strands.tools.mcp.mcp_types

Type definitions for MCP integration.

ToolsChangedCallback

Section titled “ToolsChangedCallback”
class ToolsChangedCallback(Protocol)

Defined in: src/strands/tools/mcp/mcp_types.py:19

Called after the server announces a tool list change and the client refreshes it.

Implemented by a plain function as well — the **kwargs tail lets the calling convention grow new keyword arguments without breaking existing callbacks.

__call__

Section titled “__call__”
def __call__(previous_names: list[str], refreshed_tools: list["MCPAgentTool"],
             **kwargs: Any) -> None

Defined in: src/strands/tools/mcp/mcp_types.py:26

Handle a refresh, given the previous tool names and the refreshed tool instances.

ToolsChanged

Section titled “ToolsChanged”

A tools-changed handler: the **kwargs-ready protocol or a plain two-argument callable.

MCPClientCredentials

Section titled “MCPClientCredentials”
class MCPClientCredentials(TypedDict)

Defined in: src/strands/tools/mcp/mcp_types.py:35

OAuth client credentials for machine-to-machine authentication.

Used with the MCPClient auth parameter, or the auth key of a server entry in a load_servers config, to authenticate against a streamable HTTP MCP server with the OAuth client_credentials grant.

Attributes:

  • client_id - The OAuth client ID.
  • client_secret - The OAuth client secret.
  • scopes - OAuth scopes to request, joined with spaces. Advisory only: if the server advertises its own scopes (via the WWW-Authenticate header or its protected-resource / authorization-server metadata), the server’s list is used instead and this value is ignored.

MCPToolResult

Section titled “MCPToolResult”
class MCPToolResult(ToolResult)

Defined in: src/strands/tools/mcp/mcp_types.py:92

Result of an MCP tool execution.

Extends the base ToolResult with MCP-specific structured content support. The structuredContent field contains optional JSON data returned by MCP tools that provides structured results beyond the standard text/image/document content.

Attributes:

  • structuredContent - Optional JSON object containing structured data returned by the MCP tool. This allows MCP tools to return complex data structures that can be processed programmatically by agents or other tools.
  • metadata - Optional arbitrary metadata returned by the MCP tool. This field allows MCP servers to attach custom metadata to tool results (e.g., token usage, performance metrics, or business-specific tracking information).
  • isError - Whether the MCP tool reported an application-level error via CallToolResult.isError. True means the tool executed but its logic returned a failure. Absent when the tool succeeded or when the error was a protocol/client exception rather than a tool-reported failure, letting callers distinguish application errors from transport/protocol errors.
  • cancelled - True when the local per-call cancellation signal was observed. This confirms local cancellation, not that remote execution stopped.