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

readOnlyHint=true already tells the agent this is a safe read; the description adds the returned fields (amount, status, check number) and the underlying endpoint, which is useful given there is no output schema. It still omits failure behavior (404 on nonexistent check) and whether the response is eventually consistent or refreshed.

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?

Two short sentences, front-loaded with the action and resource, with the endpoint mapping tacked on usefully for error interpretation. Nothing is wasted, though the API path borders on redundancy.

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 single-parameter read tool with annotations covering the safety profile, the definition is nearly sufficient: identity, returned content, and the REST mapping are all present. Only error/exception behavior 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?

Only one parameter, and schema description coverage is 100% with the format hint 'chk_…' already in the schema. The description's 'by id' adds nothing beyond the schema, so the baseline 3 applies.

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 ('Retrieve a single check by id') and scopes it to a single record, which implicitly separates it from lob_list_checks. It does not explicitly name any sibling, but the singular retrieval semantics are unambiguous.

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?

Usage is only implied: the agent must already hold a check id (chk_…) to call it. There is no explicit statement of when to use this versus lob_list_checks or other get_* tools, and no mention of error conditions such as a missing/unknown id.

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