gleif-mcp-server

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

Annotations already declare readOnlyHint=true and idempotentHint=true, indicating safe, repeatable operations. The description adds valuable context beyond this by specifying failure modes ('no issuer found for this ISIN') and input constraints ('ISIN is not 12 characters'), which are not covered by annotations. However, it doesn't detail rate limits or authentication needs, keeping it from a perfect score.

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 highly concise and well-structured, with three distinct parts: purpose statement, usage guidelines, and failure conditions. Each sentence earns its place by providing essential information without redundancy, making it easy for an agent to parse quickly.

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?

Given the tool's low complexity (1 parameter, no output schema) and rich annotations, the description is nearly complete. It covers purpose, usage, and failures effectively. However, without an output schema, it doesn't specify the return format (e.g., what data the LEI includes), leaving a minor gap in contextual understanding.

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?

The input schema has 100% description coverage, fully documenting the 'isin' parameter with format, length, and examples. The description mentions '12 characters' and provides an example ISIN, but this adds minimal value beyond the schema. The baseline score of 3 is appropriate since the schema does the heavy lifting.

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's purpose: 'Find the issuer's LEI from a securities ISIN code (12 characters).' It specifies the verb ('Find'), resource ('issuer's LEI'), and input ('ISIN code'), distinguishing it from siblings like 'search_by_bic' or 'lei_lookup' that use different identifiers or approaches.

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 explicitly provides usage guidelines with 'USE WHEN:' and 'FAILS WHEN:' sections. It gives concrete examples of when to use the tool (e.g., 'who issued ISIN US0378331005?') and clear failure conditions (e.g., 'ISIN is not 12 characters'), helping the agent select this tool over alternatives like 'validate_lei' or 'search_entity'.

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