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

Beyond the annotations (which only declare readOnlyHint=false and destructiveHint=false), the description discloses quota consumption ('one monthly library lookup'), caching ('unless today's result is cached'), and confirmation gating ('Nothing is read until one is confirmed'). It does not explain the non-read-only nature implied by the annotation or any permission requirements.

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 description is four sentences, front-loaded with the core purpose and evidence criteria. Every sentence adds value: the evidence factors, the confirmation gating, the quota/caching cost, and the space scoping. No waste.

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?

Given no output schema, the description covers what the tool does, how it evaluates matches, its side effects (lookup quota, caching), and session scoping. It does not describe the return format (e.g., list shape, evidence fields) but the evidence parenthetical implies useful output; completeness is strong but not exhaustive.

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 coverage is 100%, so the baseline is 3. The description adds context for space_id (override vs set_active_space) but does not mention the force parameter or its cache-bypass behavior beyond a general caching note; the schema already documents all parameters.

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 states a specific verb (search) and resource (public ad library accounts matching a competitor), and the evidence criteria (website match, name match, verification) clearly distinguish it from sibling tools like list_competitors or list_competitor_ads.

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?

It gives clear usage context: scoped to the active Space, with an option to override via space_id or use set_active_space. However, it does not explicitly state when not to use this tool or name the confirmation sibling (confirm_competitor_library_account) as the required next step, leaving some inference to the agent.

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