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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: which engines contribute data, why Gemini and Grok are absent (they return no source URLs), and that results are ordered by citation frequency. It does not say whether citation frequency is aggregated over a time window or across all prompts, which matters for interpreting the ranking.

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, both earning their place: the first states the resource, ranking and data source; the second preempts the obvious 'why not Gemini?' question. The identifying information is front-loaded with zero filler.

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?

An output schema exists, so return values need not be explained, and the annotations cover the safety profile, leaving the description appropriately lean. The one meaningful gap is the absence of any statement about the aggregation window or scope of the citation counts behind the ranking.

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 100%, with both limit and cluster_id documented in the schema itself, so the baseline is 3. The description adds no meaning beyond the schema — it never explains what a cluster filter does in this context or what the default result set looks like.

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 gives a specific verb and resource ('List domains most cited by ChatGPT, Perplexity and Claude ... ranked by citation frequency') and pins down the scope with an explicit engine exclusion. It does not name a sibling tool for contrast, so the agent must infer the boundary with tools like list_missed_citations or list_competitors on its own.

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?

Usage is implied by the GEO-prompt framing rather than stated: nothing says 'call this when you want to know where AI answers source their information' or names an alternative. There are no exclusions or prerequisites beyond the engine coverage note, which is about data scope rather than when-to-use guidance.

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