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

With no annotations, the description carries the transparency burden. It discloses sorting (newest first), issuer resolution via CUSIP-6, instrument-level actions that can share dates, and the licensed-action scope. It doesn't describe response shape or limit/pagination behavior, but it provides meaningful non-obvious context.

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 dense, front-loaded sentences cover purpose, use cases, and resolution mechanics without filler. 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?

For a low-complexity two-parameter tool with no output schema, the description covers purpose, trigger, ordering, scope, and non-obvious resolution logic. Remaining gaps are output-field detail and explicit limit semantics, but these are minor for correct invocation.

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 only 50%; `ticker` has a tautological schema description and `limit` has no prose. The description adds real meaning to `ticker` by explaining equity-ticker-to-CUSIP-6 resolution, but it never clarifies `limit` behavior or its default. Partial compensation for the schema's weak coverage.

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 a specific resource—'Full S&P rating-action history for one issuer's debt'—and lists the exact event types (new rating, upgrade, downgrade, outlook/creditwatch change) with from/to symbols and ordering. This clearly distinguishes it from credit-related siblings like bond, CDS, or calendar tools.

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 explicit trigger guidance: 'Use when asked what a company is rated or when/why it was up/downgraded.' It does not name alternative tools or state when not to use it, but the use cases are concrete enough to guide an agent.

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