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

Goes well beyond the readOnly/idempotent annotations: publication schedule (business days ~15:30 UTC+3), the indicative-not-official caveat, 6-decimal results, string decimals, TRY-per-unit quoting with JPY per 100, and the presence of source_url/bulletin_date/disclaimer in every response. This is exactly the context an agent needs to trust and interpret output.

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?

Front-loaded with the purpose, then rules, then output shape and source/schedule. Every sentence carries useful information, though the return-value sentence and the later 'Every result includes source_url...' sentence partially overlap and could be merged.

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 5-parameter conversion tool with an output schema and strong annotations, nothing material is missing: quoting conventions, date defaulting, cross-conversion behavior, precision, and data provenance are all covered.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning: the cross-conversion convention that rate_type applies to both legs, the TRY-on-either-side rule, and the omission of date meaning 'latest bulletin'. It does not elaborate the enum semantics of rate_type (that lives in the schema), so it is not a full 5.

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?

States a specific verb and resource (converts an amount between two currencies) with the authoritative source qualifier (TCMB rates). It is clearly distinguishable from the sibling rate-listing tools because it performs a conversion and returns a computed result plus breakdown rather than a rate table.

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?

Gives concrete operational guidance: TRY may be on either side, omit date for the latest bulletin, and cross conversions route through TRY using the same rate_type on both legs. It does not explicitly say when to prefer a sibling (e.g. get_latest_rates for raw rates), so it stops short of full alternative routing.

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