Unverified50% confidenceFactExact time
In the Claude Agent SDK, the fully qualified name of an MCP tool is mcp__servername__toolname (joined with double underscores), and this full string must appear in the allowed list exactly as is, otherwise the call falls to permission mode.
1
Sources
50%
Confidence
Long-term
Relevance
10/27/2026
First Seen
Sources
Claude Agent SDK in Practice: Building Your First AI Agent Step by Step
youtubeARE AGI10/27/2026
Related Entities
Related Claims
UnverifiedWhen Claude calls MCP tools in a conversation, it uses the naming format mcp__server__tool; previously, selecting a tool using a bare name would return no matching results, and this issue has been fixed in v2.1.271.75% similarUnverifiedThe tool has a built-in function for pinning MCP tool definitions, and issues a warning when a connected MCP server subsequently modifies its tool definitions.75% similarUnverifiedThrough mcpc, both of these capabilities can be used regardless of whether an Agent's own MCP client supports progressive discovery and code mode.75% similar
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