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

Annotations only cover the read-only/idempotent profile, and the description adds substantial behavior beyond them: the weekend/holiday/today-before-15:30 fallback with a fallback_reason, the pre-2005 TRL denomination change, quote conventions (TRY per unit, JPY per 100), string-typed decimals, and the mandatory source_url/disclaimer fields. These are exactly the traps that would cause a misread result if undisclosed.

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, all carrying operational information, with the core purpose front-loaded. Slightly dense — the trailing disclaimer sentence is the weakest, though it explains fields the caller will see in the response.

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?

An output schema exists, so return values need not be enumerated; the description instead covers the edge cases an agent must anticipate — fallback, denomination change, quote unit, string decimals — which is what's actually missing from structured fields.

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; the description goes beyond it by explaining that the date is the bulletin date (not a request timestamp) and that omitting currencies yields all ~20. It also adds quote-interpretation semantics (per unit, JPY per 100, TRL history) that the schema cannot express.

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 — returns the TCMB daily bulletin published on a given date — with a clear scope (history back to 1996). That framing separates it from get_latest_rates (always the newest) and convert_currency (cross-rate computation) without needing to name them.

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?

Describes the operative scenario well: supply a date, and if no bulletin exists that day, a fallback to the prior bulletin is returned with is_fallback=true. It does not explicitly say when to prefer get_latest_rates or convert_currency instead, nor does it warn against using this for live intraday rates beyond the ~15:30 TRT note.

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