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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds valuable context beyond annotations: 'no auth required', 'Source: TreasuryDirect TA_WS', and 'US Government open data'. 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?

Three sentences with the purpose front-loaded, followed by a useful list of returned fields and source/auth context. It repeats the type duration mappings already present in the schema, which is slightly redundant, but the overall structure is efficient and each sentence earns its place.

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?

With an output schema present and rich annotations already provided, the description adds the essential missing context: source, auth requirement, covered security types, and output fields. For a simple read-only tool with two optional parameters, nothing critical is missing for an agent to correctly select and invoke it.

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 description coverage is 100% and the schema already explains both parameters, enum values, and defaults. The description mentions 'type' and 'look-back period' but adds no new detail beyond the schema, so baseline 3 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 'Returns' and resource 'Completed US Treasury security auction results' with clear filters 'by type and look-back period.' It enumerates output fields and security types, and the word 'Completed' distinguishes it from the sibling 'treasurydirect.auction.upcoming'.

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 clearly implies use for completed auction results and specifies the type and look-back filters, but it does not explicitly name alternative tools like treasurydirect.auction.upcoming or state when not to use it. The 'Completed' qualifier provides useful context, yet there are no explicit exclusions or alternatives.

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