whois

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. Beyond that, the description discloses real behavioral traits: unknown names raise NOT_FOUND and surface recently active agents as a hint, t3_thread is null outside T3, and profile activity does not mean the session is live. That last caveat is a genuinely useful warning not derivable from annotations.

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 tight sentences, front-loaded with what the tool returns, followed by error behavior and the sibling pointer. The mid-sentence field enumeration is dense but each clause carries information; nothing is 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 must carry the return shape, and it does by listing every returned field plus the null semantics of t3_thread. Error behavior, the staleness caveat, and the sibling alternative are all present, so an agent has what it needs to call and interpret this correctly.

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 both parameters are documented in-schema, so the baseline is 3. The description adds only indirect semantics via the NOT_FOUND behavior tied to agent_name; it does not explain the expected format for agent_name or project_key beyond the schema.

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?

Specific verb (return) plus singular resource (one agent's profile), and it enumerates the returned fields (program, model, task description, t3_thread, activity times). It explicitly distinguishes itself from list_agents, so an agent can route between the two without opening a 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?

It names the alternative for the plural case ('To see every agent in a project, use list_agents'), which is explicit routing guidance. It does not spell out exclusions or preconditions (e.g. when an agent lookup is unnecessary), so it falls short of the full when/when-not treatment.

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