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

Annotations declare destructiveHint=true and idempotent=false, and the description adds context the annotations cannot: the reason is mandatory and persisted in an audit trail, the credential scope required, and the sandbox-key 403 behavior. That is meaningful behavioral disclosure beyond structured fields.

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?

Purpose is front-loaded in the first clause, followed by the requirement and auth/error context in tight, non-redundant sentences. Every sentence adds information the agent needs to call the tool correctly.

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 two-parameter, non-idempotent mutation with no output schema, the description covers purpose, parameters, credential scope, audit-trail effect, and the pre-claim 403 error. Nothing an agent needs to invoke it successfully 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 coverage is already 100%, so both parameters are documented by the schema; the description adds value by noting reason is retained in the audit trail and that proposal_id comes from list_commerce_proposals. It does not add further format or constraint detail, but the schema carries that.

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 ('Reject a drafted price proposal') that is inherently distinguishable from the sibling approve_commerce_proposal and from apply_analyst_proposal/execute_commerce_proposals. An agent knows exactly what action is taken and on what object.

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 concrete preconditions for use — a Last Price credential with commerce proposal reject scope and a claimed workspace, with the explicit failure mode of a 403 for sandbox keys. It also routes the agent to list_commerce_proposals for the id. It stops short of naming when to prefer an alternative action (e.g., approve or executive proposals), so no explicit exclusions.

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