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

Annotations already establish this is a safe read (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so an agent knows the safety profile. The description adds real value beyond that by surfacing the terms-verified date (a freshness signal) and an operational directive to quote money amounts verbatim rather than paraphrase — context annotations cannot carry. It omits failure behavior for unknown ids, keeping it from a 5.

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?

Two sentences with no filler: the first establishes the precondition and the payload, the second is a crisp output-handling rule. It opens with usage rather than a one-line statement of what the tool returns, so the core purpose is marginally back-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?

An output schema exists, so return fields need not be re-explained, and readOnly annotations cover the safety profile; what remains is when to call it can't be misread. The only gap is behavior on an invalid or unknown id, which is minor for a single-param read tool.

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 a single parameter at 100% schema description coverage, the schema already documents the id format and even points to search_bonuses for discovery. The description adds no parameter-level syntax or constraints beyond that, 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?

The description conveys a specific read operation on a single bonus offer and enumerates the fields it exposes (requirements, minimum deposit, direct-deposit rules, expiry, state availability, terms-verified date), which implicitly distinguishes it from search_bonuses/compare_bonuses. It never states the verb+resource directly ('fetch the full record for a bonus id'), leaving the purpose implied by the field list rather than declared.

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?

Gives an explicit trigger: 'Use before recommending an offer', which tells the agent when this tool belongs in a workflow. It does not name alternatives such as search_bonuses (that routing hint lives only in the id parameter schema) and offers no when-not guidance, so it stops short of full routing clarity.

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