Get API Usage / Rate Limits (Apollo)

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, destructiveHint false. Description adds that it 'consumes no credits' and requires a master API key, and clarifies what it cannot do (credit balance). No contradictions; adds valuable context beyond 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 sentences with zero waste. Purpose is front-loaded. Each sentence adds distinct value: purpose, usage guidance, and limitation/alternative. Highly efficient.

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 tool with no parameters and no output schema, the description covers key information: what it reports, when to use, prerequisites, and what it cannot do. Annotations provide additional safety signals. Slightly more detail on the output format (e.g., what fields are in the headers) could be added, but overall complete.

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?

Input schema has zero parameters, so baseline is 4. Description adds meaning by explaining what the tool returns (rate limit headers, per-endpoint usage). While no parameter details are needed, the description provides context about the output, which is sufficient.

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?

Description clearly states 'Report per-endpoint Apollo API usage against the minute/hour/day rate limits, plus the most recent rate-limit headers observed.' This specifies a specific verb ('Report') and resource ('API usage / rate limits'). It distinguishes from sibling tools which are all search/enrich operations.

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 states when to use: 'Use before large batches to check headroom, and to answer "how much have we used?"' Also provides exclusion: 'Note: Apollo exposes no API for the remaining credit balance — that is only visible in the Apollo UI.' Prerequisites are given: 'Requires a master API key; consumes no credits.'

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