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

Annotations already cover the safety profile (readOnlyHint, non-destructive, openWorld), so the description earns credit for adding real context: ECB as the source, daily reference-rate cadence, the 30+ currency coverage, arbitrary base currency, and a 90-day history window. It does not disclose what happens for unsupported currencies or unsupported dates, keeping it short of a 5.

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?

It opens with the title text restated and then a fragment ("Convert amount."), which is redundant padding, while the genuinely informative facts (rate source, cadence, history window) are buried in the trailing fragment. It is short but not well front-loaded or edited.

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?

With no output schema, the description must carry the interaction burden, and it does cover source, currency coverage, and history window. It omits how a conversion result is presented and how the date parameter behaves relative to the 90-day window, which leaves gaps for a calculation tool whose result shape matters.

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%, so all four parameters are already documented in the schema and the baseline is 3. The description adds mild meaning ("any base currency", "history of the last 90 days" implying the date parameter selects historical lookups) but no format or constraint detail beyond that.

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 gives a specific verb and resource ("Convert amount" with ECB reference rates) and scopes it with "30+ currencies, any base currency". It is clear what the tool does, but it never distinguishes itself from the sibling tool exchange_rates, leaving the agent to guess which one to pick for raw rates vs. 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?

There is no explicit when-to-use guidance and no named alternative, despite exchange_rates being an obvious overlapping sibling. Usage is only implied by the word "Convert", so an agent has no stated rule for choosing between this tool and exchange_rates.

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