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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so safety is covered structurally. The description adds genuinely new context beyond that: the call is free and never creates a new charge, which is the key behavioral risk an agent needs to know before retrying a paid flow.

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 clauses, front-loaded with the operation and its cost model, then the when-to-use, then the filtering options. No sentence is redundant or padding.

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 zero-required-parameter lookup with full annotation coverage, the definition gives an agent everything needed to invoke it correctly. With no output schema, it could briefly say what a successful lookup returns (a recovered response vs. a not-found result), which is the only remaining gap.

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% and both parameters are described as optional, so the schema does most of the work. The description adds the useful combinatorics ('agent_id, transaction hash, or both') and the 'pass it unchanged' intent for the hash is carried in the schema, so value beyond the schema is modest but real.

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 verb and resource ('read-only recovery lookup for a possibly lost paid response') and implicitly distinguishes itself from the payment-creation siblings by stating it 'never creates a new charge.' An agent can tell what it does and does not do without opening the schema.

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?

It gives explicit timing guidance ('Use this before re-authorizing payment'), which tells the agent when to reach for it relative to manage_purchase. It does not name a specific alternative tool or state a when-not condition, so it stops just short of the top score.

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