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

Beyond the readOnly/openWorld annotations, it discloses an entitlement requirement (keyword_research facility) and, importantly, a conditional data-quality behavior: exact volume and CPC only appear when a Keywords Everywhere key is configured. That tells the agent to expect degraded estimates in some configurations, which annotations alone would never reveal.

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?

The payload description is front-loaded and the follow-up tool routing and prerequisite come after, which is a sensible structure with no filler. The first sentence is dense with enumerations but each element earns its place by describing the return payload.

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 takes on the burden of describing return values and does so thoroughly: idea clustering, volume/difficulty/CPC, content actions, and per-keyword verdicts. It also covers the entitlement precondition and the degraded-data case, leaving nothing an agent needs before calling it.

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?

There is a single productKey parameter with 100% schema description coverage, so the schema already carries the semantics. The phrase 'for one product' reinforces the single-product scoping but adds no format, lookup, or error guidance beyond what the schema provides.

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 (stored keyword research for one product) and enumerates its contents: intent-clustered ideas, volume/difficulty, CPC, prioritized content actions, and per-keyword verdicts. It is clearly distinguished from run_keyword_research (creates a new run) and from rank-tracking tools, so an agent can choose it 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?

Explicitly routes the agent to run_keyword_research for a fresh run and to add_tracked_keywords for follow-up on interesting ideas, and states the prerequisite ('Requires a plan with the keyword_research facility'). It does not explicitly say what happens when no research has been stored yet, but the when-to-use context and alternatives are clear.

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