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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds real value beyond that by disclosing the scope constraint 'latest TCMB bulletin' — only currencies present in the newest bulletin are listed — plus the shape of each entry; it does not add pagination or error context.

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?

Two sentences: the first defines the resource and its contents, the second routes the agent to the follow-up action. Nothing is wasted and the essential scoping info comes first.

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 zero-argument, read-only list tool with full annotation coverage and a declared output schema, nothing material is missing — scope, entry contents and intended use are all stated.

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 tool takes zero parameters and the schema is empty at 100% coverage, so there is no parameter semantics to explain. Baseline 4 applies.

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 ('Lists currencies in the latest TCMB bulletin') and enumerates the per-entry content: English/Turkish names, quoting unit, and published rate types. This is clearly distinguishable from get_latest_rates, get_rates_on_date and convert_currency, which return values rather than a currency inventory.

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?

'Use it to check codes before calling the other tools' explicitly positions it as a prerequisite/discovery step relative to its siblings. It stops short of naming exclusions or prerequisites (e.g. whether the latest bulletin is always populated), so it is not a full 5.

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