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

Annotations cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description goes well beyond them: zero credit cost and repeat-safety, data provenance distinguishing measured DataForSEO figures from model-written judgement, the edge case that an empty result is a real answer not a failure, and the stale-audit limitation.

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 most decision-relevant fact ("Costs nothing") and organized around what is returned, provenance, and caveats. It is on the dense/long side with some run-on listing of returned fields, but nearly every sentence adds routing or trust information.

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?

No output schema exists, so the description takes on the burden of describing return content — which it does thoroughly (ads, keywords, volumes, CPC, landing pages, head-to-head summary, captures) and annotates with provenance and confidence caveats. Nothing an agent needs to call it correctly is missing.

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?

One parameter with 0% schema description coverage, so the description must carry the burden. It does imply the requirement ("Needs a completed audit", "Older audits carry no ad data"), which tells the agent audit_id must reference a finished audit, but it never states where audit_id comes from or its format. Adequate but with a clear gap.

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 resource (the competitor layer of a finished audit) with an explicit enumeration of contents: rivals bidding on the same clicks, live ads, keywords, search volume, CPC, landing pages, top advertiser, and paid keyword count. It also names the sibling it is not (ask_audit), so an agent can route correctly without opening either 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?

Gives an explicit prerequisite ("Needs a completed audit"), an explicit alternative with a selection rule ("ask_audit with topic:competitors is the one for the written comparison; this is the one for the numbers"), and an exclusion (older audits carry no ad data). All the when/when-not decisions are stated.

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