Retrieve the current API key

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

Annotations already declare readOnly, idempotent, non-destructive, and openWorld, so the safety profile is covered. The description adds two pieces of context the annotations do not: no scope/authorization is required, and the response conveys remaining call quota — a quota-check behavior worth knowing. It doesn't describe what else is returned, keeping it short of 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?

Two sentences, no filler, and the actionable guidance is front-loaded after the purpose line. Every sentence earns its place by adding a use case or a constraint not already in the structured fields.

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 zero-parameter, read-only tool with full annotation coverage, the description supplies the key missing context: this is a health/quota check requiring no scope. With no output schema, it hints at the return value (calls left today) but does not fully describe what the payload contains, which is the only 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?

The tool takes no parameters, so according to the rubric the baseline is 4. There is nothing for the description to compensate for, and it correctly avoids inventing arguments.

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 ('Retrieve the current API key') and goes beyond the title by explaining what the call is for: verifying the key works and checking remaining daily quota. The sibling tools (matches_search, open_requests_*) belong to an unrelated domain, so no differentiation is needed or expected. It loses a point only for leading with a restatement of the title.

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?

Explicitly says when to use it: 'check that your key works and how many calls are left today,' which gives an agent a concrete triggering condition. It also notes the prerequisite is trivially satisfied ('It needs no scope'). No alternative tool is named, but no sibling competes for this task.

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