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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and no destruction. Description adds value by detailing the record fields (dt, txt, txten, id_api, value, freq) and date semantics, complementing annotations effectively.

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 plus a record format note. Every sentence is necessary and efficient. No redundancy or fluff.

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 all core aspects: what data, how to filter by date, output structure. Lacks mention of error cases or monthly granularity, but adequate for a simple read tool with complete annotations.

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 covers 100% of parameters. Description adds meaningful context: the date parameter selects a reference month and omitting gives the latest month. This clarifies behavior beyond the schema's description.

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 it retrieves NBU international reserves for a given month, broken down by component, with a record structure. It is distinct from sibling NBU tools (currency rates, history, etc.) but does not explicitly differentiate 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?

Provides clear guidance on the date parameter (selects month, omit for latest). No explicit guidance on when to use vs. alternative tools, though resource name implies context. Minimal comparative usage advice.

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