treasury_avg_interest_rates

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

Annotations provide readOnlyHint and openWorldHint. The description adds beyond annotations by detailing memoization (5 min), latest mode behavior (pinned to latest record_date), and that avgInterestRatePercent can be null. No contradiction with annotations.

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?

The description is two sentences with no fluff. First sentence clearly states purpose and output fields. Second sentence explains the two modes and optional filter. Every sentence adds value.

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?

Despite no output schema, the description lists all return fields and their types. It covers both modes, pagination, and filtering. For a read-only query tool with good annotations, this is complete.

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% with descriptions for each parameter. The description adds meaning by explaining how latest and range modes work together, that securityType is an exact match on security_type_desc, and the implications of pagination parameters (pageSize, pageNumber) in range mode.

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 the tool returns 'average interest rate the US Treasury pays by security type/description' and lists the specific fields returned. It distinguishes itself from sibling tools by focusing on a specific Treasury dataset and explaining the 'keyless Treasury Fiscal Data' nature.

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?

The description explains two usage modes: 'latest' (default) for the most-recent month's breakdown with memoization, and range mode with start/endDate for historical data. It also notes optional securityType filter. While it doesn't explicitly state when not to use this tool, it provides sufficient context for correct usage.

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