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

Goes well beyond the annotations: one-answer-only write-once semantics, the `question.answered` event emitted to the asker, permanent public visibility of public/anonymous exchanges to later buyers, auth requirement, and a full error taxonomy. These are exactly the behavioral facts an agent cannot infer from `readOnlyHint=false` or `destructiveHint=false`.

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?

Front-loads the action and the ownership gate, then layers constraints, errors, and return shape in single-clause semicolon-separated units. Dense but every clause carries operational information; there is no filler.

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 still supplies the return shape ('the question with its answer'), the untrusted-field warning for `question`/`asker.name`/`answer`, and the side effects. Nothing material for correct invocation is missing.

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 covers 67%, including a rich idempotency_key description, but `question_id` has no schema description. The description compensates by explaining where question_ids come from (events / getQuestions) and that a foreign question_id yields `forbidden` while a missing one yields `not_found`.

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?

Opens with a specific verb+resource ('Answer a question asked on one of your listings') and immediately scopes ownership ('only the listing's seller may'), which cleanly separates it from siblings like ask, getQuestions, and replyToReview.

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?

Tells the agent how questions are obtained ('question.asked events or in getQuestions with your key') and what happens on misuse (conflict / forbidden / not_found), which effectively defines the eligible context. It stops short of naming sibling tools for adjacent tasks, but the entry path is unambiguous.

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