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

Annotations already declare readOnlyHint=false, idempotentHint=false and openWorldHint=false, so the mutation profile is covered structurally. The description adds one useful behavioral fact – flagged listings are reviewed – but says nothing about whether reporting is anonymous, whether duplicate reports are allowed, or what a caller gets back. Modest added value against an already-informative annotation set.

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 short segments with the trigger condition front-loaded right after the name. The example call is mildly redundant given a complete schema but is compact and not wasteful.

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 non-idempotent mutation with no output schema, the description covers what to report and why, but leaves open what happens on success, whether repeated reports are meaningful, and how the reviewer outcome reaches the caller. Adequate but with real gaps for a write operation.

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 listing_id, reason (max 280 chars) and key are fully documented in the schema. The inline example only echoes listing_id and reason as placeholders and adds no new meaning about formats or constraints. Baseline 3 applies when the schema does the work.

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 opening 'Barter report' is largely a restatement of the name, but the WHEN clause supplies the real purpose: reporting a listing that violates policy. That verb+resource combination ('report a listing') is specific enough to separate it from siblings like barter_list or barter_offers, though it never names those alternatives.

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?

The explicit 'WHEN: report a listing that violates policy (prohibited or illegal items/services)' gives a clear trigger condition with concrete examples of what qualifies. There is no when-not guidance and no routing to alternative tools, which keeps it short of a 5.

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