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

Goes well beyond the annotations by disclosing the partial-update semantics, the destructive nuance that 'rules replace the whole rule list' (which is the key consequence behind destructiveHint=true), and both auth and workspace-claim requirements including the specific 403 refusal. That is exactly the context an agent cannot infer from idempotentHint/destructiveHint alone.

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?

Four short sentences, front-loaded with purpose then mutation semantics then prerequisites. Every sentence carries operational weight; only the two separate 'Needs a ...' sentences could be merged, but nothing is wasted.

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 10-parameter destructive mutation with nested objects and no output schema, it covers the high-risk gaps: what is merged vs replaced, credentials, and workspace state. It does not describe the response or the interaction between approval_mode auto and auto_approve_max_delta_pct, both of which remain for the schema to convey.

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 the baseline is 3, but the description adds real meaning: policy_id provenance from list_commerce_policies and the replace-not-merge behavior of the rules array, which the schema does not state. Other parameters (scope, approval_mode, floor/ceiling) get no description-level elaboration.

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 ('Change a commerce pricing policy') and immediately clarifies update semantics ('Only the fields you send change; rules replace the whole rule list'), which separates it from a full create/replace. It never names the sibling alternatives (create_commerce_policy, test_commerce_policy, delete_commerce_policy), so differentiation relies on the name rather than explicit routing.

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?

Provides concrete preconditions: a Last Price credential with 'commerce configure' scope, a claimed workspace with the exact 403 failure mode, and where to obtain policy_id (list_commerce_policies). It stops short of saying when to prefer this over create_commerce_policy or test_commerce_policy for validation, so no explicit alternatives/exclusions.

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