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

Annotations already declare readOnlyHint and destructiveHint, and the description adds meaningful behavioral context such as HTTP 503 error handling when upstream sources are unavailable, the x402 SLA cost, and the data_source provenance field. It does not contradict the annotations, though it stops short of detailing the complete success response structure.

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 fairly detailed and front-loads the main content, but it contains redundant error messaging: 'Returns HTTP 503 (no charge) if upstream source unavailable for >50% of fields' is repeated in slightly different words later. This redundancy makes it less concise than it could be.

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 tool with one optional parameter and no output schema, the description provides a good overview: it lists the data series returned, update frequency, source, error behavior, pricing, and provenance field. It is not exhaustive, but it is sufficiently complete for an agent to invoke the tool correctly.

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?

With schema description coverage at 0%, the description must clarify the single parameter. It mentions 'OAS by rating tier' which relates to rating_tier, but it does not explain the enum values (all, ig, hy, bbb) or how the parameter affects other metrics like TED spread and 2s10s. The enum is somewhat self-explanatory, but the description does not fully compensate for the lack of schema documentation.

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 provides live investment-grade and high-yield credit spread benchmarks from FRED ICE BofA indices, listing specific metrics (OAS by rating tier, TED spread, 2s10s Treasury spread, distress signal). It distinguishes itself from sibling benchmark tools by focusing on credit spreads and targeting credit analysts and fixed income PMs.

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 provides clear context for when to use the tool: for credit analysts and fixed income PMs, with daily updates and a live source. However, it does not explicitly mention alternatives or when not to use this tool, which prevents a higher score.

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