FX Converter MCP

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

Annotations declare readOnlyHint=true, and the description adds context about real, current ECB reference rates and that the rate has a date. It discloses the source and return fields, adding value beyond the annotation. 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?

Four sentences, front-loaded with the core action, then usage examples, parameter format, and return value. No fluff, every sentence contributes.

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?

Covers purpose, usage, parameters, and return values. With an output schema present, the description goes beyond by explicitly stating the return fields (converted amount, rate, date). Lacks only minor edge-case details like supported currency scope, but overall quite 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?

The description explains from_currency/to_currency are 3-letter ISO codes with examples, compensating for the 0% schema coverage. The amount parameter is implied by 'amount' and examples, though not explicitly described in text.

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?

Clearly states the tool converts an amount from one currency to another using ECB reference exchange rates. Examples distinguish it from a rate-only lookup. Specific verb 'convert' and resource 'currency' are present, differentiating from sibling get_exchange_rate.

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?

Explicitly states 'use for any how much is X in Y question' with examples, providing clear context. However, it doesn't mention when not to use it or reference the sibling get_exchange_rate for rate-only queries, so it falls short of full alternatives guidance.

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

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

The readOnlyHint annotation already establishes the safe read-only nature, and the description adds value by disclosing that it returns 'the rate and the date it's from'. It also clarifies that no amount conversion occurs. No contradiction with annotations detected.

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 four short sentences, each adding necessary information: purpose, example usage, parameter format, and return value. No waste or redundancy; it is perfectly front-loaded with the primary action.

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 simple two-parameter lookup tool with a read-only annotation and an output schema, the description covers purpose, usage context, parameter semantics, and returns. This is sufficient for an agent to select and invoke it correctly.

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?

Input schema provides zero description coverage, so the description compensates by stating that from_currency/to_currency are 3-letter ISO codes and giving a concrete example (USD/EUR). It does not explicitly explain the directionality of the rate, but for a tool named get_exchange_rate this is reasonably inferable.

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 function with a specific verb ('look up') and resource ('exchange rate between two currencies'). It explicitly distinguishes itself from the sibling convert_currency by noting 'without converting a specific amount', making the purpose unambiguous.

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 gives a clear usage scenario ('what's the exchange rate between USD and EUR' style questions) and implicitly excludes conversion tasks by saying 'without converting a specific amount'. However, it does not explicitly name convert_currency as the alternative, so it stops short of fully explicit when-not/alternatives guidance.

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