Frankfurter MCP

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

Annotations already declare readOnlyHint=true and openWorldHint=true, indicating safe read operations and open-world data. The description adds context about filtering with symbols and default behavior, but does not disclose additional behavioral traits such as rate limits, data freshness, or error handling. 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 appropriately sized with two sentences that are front-loaded and efficient. It avoids redundancy and wastes no words, though it could be slightly more structured by explicitly separating purpose from usage notes.

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 complexity (simple read operation), rich annotations (readOnlyHint, openWorldHint), and high schema coverage, the description is adequate but lacks details on output format, data sources, or limitations. Without an output schema, it should ideally hint at the return structure, but annotations provide some safety context.

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 detailed descriptions and enums for both parameters. The description adds minimal value by mentioning that symbols filter results and default to all currencies if not provided, which is already implied in the schema. Baseline 3 is appropriate as 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 with a specific verb ('Returns') and resource ('latest exchange rates for specific currencies'). It distinguishes itself from historical tools but doesn't explicitly differentiate from sibling tools like 'get_supported_currencies' or 'convert_currency_latest' in terms of what makes this tool unique for retrieving rates versus conversion.

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 implied usage by explaining that symbols filter results and default behavior when symbols are not provided. However, it lacks explicit guidance on when to use this tool versus alternatives like 'get_historical_exchange_rates' or 'convert_currency_latest', and does not mention any prerequisites or exclusions.

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