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

readOnlyHint=true already tells the agent this is a safe read, so the lower bar applies. The description adds the underlying REST mapping (GET /v1/people/{id}), which is mild context, but says nothing about not-found/error behavior or the shape of the returned person beyond the word 'person (contact)'.

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 with the core action front-loaded and no filler. The trailing REST endpoint reference is marginally redundant for an MCP caller but is compact and does anchor the tool to a known API.

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 no output schema and annotations covering the safety profile, the description is sufficient to call the tool correctly. Some detail about the returned person fields could be added, but nothing essential 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?

Schema description coverage is 100% and the single 'id' parameter is documented in the schema, so the schema carries the semantics. The description's 'by id' restates rather than extends that, 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 person (contact) by id'), and the 'single'/'by id' framing distinguishes it from the plural folk_list_people and the write-oriented folk_create_person. It stops short of naming the sibling it is not, so it is clear but not fully self-differentiating.

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 implied by 'by id' — the agent can infer this is the lookup path when a person id is known, versus the list tools. There is no explicit when-to-use/when-not statement or reference to alternatives, leaving routing to inference.

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