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

With no annotations supplied, the description carries the full burden and does so well: it discloses the 1 CRD cost per call, that the charge applies even on rejected calls, the 429 exemption, that partial updates leave untouched fields alone, and that errors return a request_id for support. This is exactly the behavioral context an agent cannot get from the schema.

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 dense sentences, front-loaded with the core action, then parameter shortcuts, then cost and error handling. Every clause carries operational information with no filler or repetition of the schema.

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 13-parameter mutation tool with no annotations and no output schema, the description covers cost, failure billing, error payloads, and partial-update semantics. It leaves minor gaps around auth via api_key/project_id and what the response contains, though the schema documents those parameters.

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?

Adds meaning beyond the 62%-covered schema for the highest-risk parameters: credit_type_ids semantics ('[] = all credit types') and is_active ('stop selling it without deleting'), plus the global 'only fields you pass change' rule that clarifies every optional field. It does not explain the remaining undocumented fields such as credits, currency, or is_popular.

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 ('Update a pricing tier by id') plus the partial-update rule, so the agent knows exactly what the tool does and how it differs from create/delete siblings. The phrase 'without deleting' implicitly contrasts it with delete_pricing_tier.

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 concrete when-to-use conditions for specific operations: pass credit_type_ids to re-scope, is_active: false to stop selling without deleting, and references create for price rules. It stops short of naming create_pricing_tier/delete_pricing_tier explicitly as alternatives for the agent to choose between.

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