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

readOnlyHint=true already establishes this as a safe read, so the description is free to spend its words elsewhere — and it does, disclosing the shape of the returned payload (signer data, waiver id, timestamps, document and certificate links), which matters because there is no output schema. It omits error behavior for an invalid id and any permission/auth notes, keeping it below a 5.

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?

Front-loaded with the core action and return contents in one dense sentence, followed by the id-sourcing hint and the endpoint. The trailing 'API: GET /participants/{id}' is marginally redundant with the tool name but cheap and occasionally useful; otherwise there is no filler.

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, the description carries the burden of describing returns and does so at a useful level of granularity, and it explains where the required id comes from. It stops short of covering failure modes (not found, permissions) or whether minor vs adult records differ in the response, which for a single-record lookup would be the remaining gap.

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 coverage is 100% and the single parameter is already documented as a UUID from the list tool, so the baseline is 3. The description adds one genuinely new fact — that the id can also come from a waiver — which is not in the schema text and helps the agent assemble the call from a second path.

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 one participant (adult or minor) by id') and enumerates what comes back: signer data, waiver id, timestamps, document and certificate links. That distinguishes it cleanly from the four list/waiver siblings, which return collections rather than a single record.

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?

'Get the id from the participant lists or from a waiver' explicitly routes the agent to otterwaiver_list_latest_participants or otterwaiver_get_waiver as the source of the identifier, so the ordering of calls is clear. There is no explicit when-not or statement about what happens with a stale/unknown id, so it falls short of a 5.

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