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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered; the description adds genuinely new behavior by disclosing that disputed=true signals source disagreement and that close matches are returned for unknown models. It doesn't say whether an unknown model returns an error or empty results beyond the close-match hint, but the key edge cases are surfaced.

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 tight sentences: what it returns, the disputed/close-match edge cases, then the sibling routing. Nothing is repeated and the essential facts are front-loaded.

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 no output schema, the description carries the return-shape burden and does so for the main fields (price, source, last-confirmed date, disputed flag, close matches). The only gap is that it never positions the tool against find_cheaper, leaving one sibling relationship unexplained.

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 both model_name and the past-date as_of are already documented in the schema. The description reinforces the single-model scope and USD-per-million-token basis but adds no format or syntax detail for as_of beyond what the schema states, so the 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 and resource ("list price for one LLM") plus the unit semantics (USD per million tokens), which an agent can act on immediately. It also tells the agent what the payload includes (source, last-confirmed date), distinguishing it from siblings that aggregate or compare prices.

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?

Explicitly routes workload costing to estimate_cost, which is the most likely confusion given the sibling set. It does not mention find_cheaper at all, so the agent gets no guidance on when to look up a single price versus search for a cheaper alternative.

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