Frankfurter MCP

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

Annotations provide readOnlyHint=true and openWorldHint=true, indicating this is a safe read operation with potentially dynamic data. The description adds that it uses 'latest exchange rates', which implies real-time or recent data, but doesn't specify source, update frequency, or accuracy limitations. No contradiction with annotations exists.

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 a single, efficient sentence that directly states the tool's function without unnecessary words. It's front-loaded with the core action and includes the key constraint ('latest exchange rates').

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 read-only tool with no output schema and rich schema coverage, the description is minimally adequate. It covers the basic operation but lacks details on output format (e.g., numeric result with currency), error handling, or sibling tool differentiation, which could aid the agent in proper usage.

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 description coverage is 100%, with clear parameter descriptions and enums for currencies. The description adds no additional parameter semantics beyond what's in the schema, such as format examples or constraints. With high schema coverage, the baseline score of 3 is appropriate.

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 with a specific verb ('converts') and resources ('amount from one currency to another'), and specifies it uses 'latest exchange rates'. However, it doesn't explicitly differentiate from its sibling 'convert_currency_specific_date', which is a similar conversion tool but for historical dates.

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 provides no guidance on when to use this tool versus its siblings. It mentions 'latest exchange rates' but doesn't explicitly state that this is for current conversions only, nor does it reference the historical alternative 'convert_currency_specific_date' or other related tools like 'get_latest_exchange_rates'.

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