Lookup users

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds the XOR input constraint and the 'never invent handles' caution, but it does not disclose output shape, missing-identifier behavior, or any API-level quirks beyond 'comma-separated v2.'

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 short sentences with the primary action front-loaded and no filler. The constraints are dense but each earns its place.

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 simple read-only lookup with two parameters, the description covers the crucial input rule and guardrail. However, with no output schema and no mention of return values or errors, an agent still has to infer what the batch lookup returns and how failures are surfaced.

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 0%, so the description must compensate. It does clarify the key relationship between user_ids and usernames (XOR) and the batch style, but it leaves format details (e.g., exact identifier forms and what 'comma-separated v2' means against the array schema) implicit.

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?

The description opens with 'Batch lookup,' naming a specific verb and indicating the plural resource, which distinguishes it from the singular x_organic_lookup_user sibling. The XOR input instruction reinforces that this is a bulk identifier-based user lookup.

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?

The description indicates how to invoke the tool ('Pass usernames XOR ids') and gives a guardrail ('Never invent handles'), but it does not explicitly say when to prefer this over x_organic_lookup_user or x_organic_search_users. The usage context is implied by 'Batch lookup' rather than stated as a decision rule.

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