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

With no annotations, the description carries the full burden and does well: it discloses the external side effect (the buyer is emailed the message plus contact details) and two operational limits (one response per ad, 20/day). It omits whether auth/user identity is required or whether a response can be withdrawn, but the critical outbound-communication risk is surfaced.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 sentences, each earning its place: action, precondition, and limits. The purpose is front-loaded and nothing is repeated from the schema or title.

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 write-with-external-notification tool with no annotations and no output schema, the description covers the side effect, preconditions, and rate limits well. Minor gaps remain around permission/auth expectations and what the caller sees after success, but an agent has enough to call it 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?

Schema description coverage is 100%, with each parameter documented including the id source (search_wants), contact guidance, message length cap, and when to omit asking_price. The description adds essentially nothing beyond the schema, so 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: responding to someone else's open wanted ad on the user's behalf, with the concrete effect of saying they have the item. It is clear in isolation, but it never differentiates itself from the sibling reply_to_response, a plausible confusion point in this toolset.

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 precondition ('only use this when the user actually has (or can get) the item and has asked to respond') plus hard constraints (one response per ad, 20 per day). An agent can decide whether to call this without any inference.

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