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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely non-obvious behavioral context: results are limited to this workspace's tracked keywords and its own keyword inspections, which tells the agent the gap is not a global market comparison. It stops short of noting any result caps or pagination.

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 core purpose, then the returned fields, then the data-source caveat. Dense but every clause carries information; the only mild cost is that the second half packs a lot into one sentence.

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, but the description enumerates the return payload (both ranks, modeled traffic, difficulty, opportunity score, shared and only-you lists), which compensates well. It is nearly complete for a one-param read tool; only result limits/ordering are unstated.

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?

With a single parameter at 100% schema coverage, the schema already explains competitor_id and its source (list_competitors). The description adds only the constraint that the competitor must be a tracked one, which is mild added meaning beyond the schema. Baseline 3 applies.

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+resource ('Keyword gap against one tracked competitor') and then pins down the exact scope: terms the competitor ranks top-30 for where your app does not. The 'one tracked competitor' framing implicitly separates it from list_keyword_gaps and expand_keyword_gap, so an agent can tell what this returns 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?

The phrasing 'against one tracked competitor' and 'Terms come only from this workspace's tracked keywords' implies when the tool is appropriate, but no sibling is named and there is no explicit when-not-to-use or alternative routing (e.g., vs list_keyword_gaps or expand_keyword_gap). Usage is inferable but not stated.

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