gleif-mcp-server

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

The description adds valuable behavioral context beyond annotations: it specifies that invalid LEIs never return errors but instead return 'valid=false with a reason message', and notes it's 'Safe to call on untrusted input'. While annotations provide readOnlyHint and idempotentHint, these additional details about error handling and safety are crucial for proper tool invocation.

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 efficiently structured with clear sections: purpose statement, usage guidelines, technical details, alternative tool reference, and behavioral notes. Every sentence adds value without redundancy, and key information is front-loaded.

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?

For a single-parameter validation tool with good annotations and no output schema, the description provides complete context: purpose, usage scenarios, technical validation details, alternative tool reference, and important behavioral notes about error handling and safety. No significant gaps exist given the tool's complexity.

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?

With 100% schema description coverage, the baseline is 3. The description adds meaningful context about what validation entails (format, check digit, database status checks) that helps the agent understand what the 'lei' parameter represents beyond just being 'LEI code to validate'. However, it doesn't provide additional syntax or format details beyond what the schema already covers.

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: 'Check if an LEI code is valid and active' with specific details about format (20 chars), check digit (ISO 17442), and database status checks. It distinguishes from sibling 'lei_lookup' by specifying this is for validation only, not full entity details.

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?

Explicit guidance is provided with 'USE WHEN' examples ('is this LEI valid?', 'verify LEI', 'check LEI format') and a clear alternative directive: 'For full entity details, use lei_lookup instead'. This tells the agent exactly when to use this tool versus alternatives.

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