segment_match_check_by_external_id

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, fully covering the safety profile. The description reinforces this with 'Fetches data. Makes no changes' and adds the HTTP method/path, providing additional context beyond annotations. No contradictions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is short and front-loaded with the purpose and route. It uses a clear structure: emoji indicator, section label, HTTP path, then purpose. However, the route notation is somewhat technical and may not be essential for an AI agent. Overall efficient but could be slightly trimmed.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, and the description does not specify what the tool returns (e.g., boolean, match status, response fields). For a simple check tool, the agent might infer a boolean or status, but explicit return information is missing. Given the rich annotations and complete schema, the description is adequate but not fully complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and each parameter has a basic description (e.g., contactId: 'ContactId'). The description adds no extra meaning or constraints beyond the schema. While the schema is complete, the description does not enhance parameter understanding, earning a baseline 3.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool checks if a Contact matches a Segment using an externalId. The verb 'Check' and the resource 'Contact matches a Segment' are specific. This distinguishes it from other segment-related sibling tools like get_segment or create_segment, as no other tool performs this exact externalId-based match check.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage for verification ('Check to see if a Contact matches a Segment'), but provides no explicit when-to-use, when-not-to-use, or alternatives. Given the many sibling tools, guidance on when to choose this over other segment tools would improve clarity.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.