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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the description does not need to restate safety. It adds useful behavioral context by disclosing that the call costs 1 request unit and by clarifying the two operational modes and parameter applicability.

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?

Three short sentences, front-loaded with the data sources and the two usage modes. Every sentence carries actionable information; there is no filler.

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 simple read-only retrieval tool with three optional parameters, the description covers sources, modes, date format constraints, and request cost. It does not describe the shape of the returned series data or listing output, which is a minor gap given there is no output schema.

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 schema already documents the three parameters and date format. The description adds meaning beyond the schema by specifying that 'series' must be an id from the list returned when omitting it, and that 'from'/'to' apply only with 'series'.

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 names the data sources (U.S. Treasury, BLS, Bank of England) and describes the two modes: listing series when 'series' is omitted, and reading one series when 'series' is provided. It is clear what the tool does, but it does not explicitly differentiate itself from likely siblings like 'macro' or 'benchmark'.

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?

It clearly states how to use each mode: omit 'series' to list available series, pass an id from that list to read one series, and that 'from'/'to' apply only when 'series' is set. It lacks guidance on when to choose this tool over siblings such as 'macro', but the within-tool usage is explicit.

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