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

readOnlyHint=true already tells the agent this is a safe, non-mutating read. The description adds what the record contains ('questions and status'), but says nothing about behavior on a missing/invalid id, whether status affects what questions appear, or any scoping/permission constraints.

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?

A single front-loaded sentence with no filler, which is the right size for a simple lookup. It arguably errs on the side of under-specification rather than verbosity, but nothing is wasted.

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?

With no output schema and no parameter documentation, the description is the only place to explain the returned record shape and the id contract, and it does neither. For a one-parameter lookup whose only input is undocumented, this is too thin.

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?

One required 'id' parameter with 0% schema description coverage, so the schema supplies no meaning at all. The description never mentions the id — not its format (UUID, slug, numeric), not where it comes from (likely list_checkins), and not what happens with an unknown value — so it fails to compensate for the coverage gap.

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 retrieval of a single check-in and names the payload contents ('its questions and status'), so the resource and cardinality ('One') are clear. It does not, however, distinguish itself from near-siblings like get_checkin_answers or list_checkins, so an agent must infer the boundary.

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?

No when-to-use guidance, no prerequisites, and no mention of alternatives. The word 'One' hints at single-record retrieval versus list_checkins, but that contrast is never made explicit, leaving the agent to infer selection criteria.

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