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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds real value by naming the required credential scope and the exact failure mode (403 for sandbox keys from self-registration until a person claims the workspace). It says little about what the returned policy content looks like beyond "scope and rules".

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 sentences, front-loaded with purpose, then id provenance, then prerequisites. Zero filler; every sentence is actionable.

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 one-param read with full annotation coverage and full schema coverage, the description covers the risky parts (auth scope, claim requirement). Minor gap: no indication of behavior when the policy id is unknown or from another workspace, and the return payload is described only in one clause with no output schema.

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% and the single property already documents "The policy id, as list_commerce_policies gives it" — the description repeats that fact rather than extending it (no format, no not-found behavior). Baseline 3 applies when the schema carries the parameter burden.

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?

Specific verb+resource: "Read one commerce pricing policy: its scope and rules", with "one" implicitly contrasting against list_commerce_policies, which is named as the id source. An agent can tell this is a single-resource fetch, though it doesn't explicitly disambiguate from update/delete_commerce_policy siblings.

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 a concrete routing rule for the required input ("policy_id is the id from list_commerce_policies") and states prerequisites: Last Price credential with commerce catalog read scope, plus a claimed workspace. No explicit when-not or alternative-tool exclusions, but the context needed to invoke it is present.

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