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

Annotations already declare readOnlyHint=true, but the description adds real value beyond them: it warns the response contains PII and specifies the return envelope (JSON:API { data }). It does not cover behavior when the id is unknown, but the safety and sensitivity profile is well disclosed.

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 compact clauses, front-loaded with the operation, followed by the data-sensitivity note and the underlying REST endpoint. No sentence is redundant and nothing important is buried.

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 readOnlyHint and no output schema, the description covers purpose, return shape, and the PII caveat, which is enough to call it correctly. Only minor gaps remain, such as not-found behavior and routing versus persona_list_cases.

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 description coverage is 100%, with case_id already documented with a 'case_...' example, so the schema does the heavy lifting. The description only says 'by id' and adds no format or constraint detail beyond the schema, making the baseline 3 appropriate.

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 ('Get a single case by id') and clarifies what a case is ('a manual-review workflow item'). The word 'single' implicitly separates it from the persona_list_cases sibling, so an agent can distinguish the two without opening any schema.

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: an agent with a case_id wanting one case can infer this is the tool. There is no explicit when-to-use guidance, no mention of persona_list_cases as the alternative for enumerating cases, and no stated prerequisites or exclusions.

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