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

The description directly contradicts the annotation. Annotations declare destructiveHint=false, but the description states 'Pass an EMPTY list to stop the watch entirely, which also clears the findings.' Clearing findings is a destructive side effect, contradicting the non-destructive annotation. Although the description otherwise discloses many behaviors (credit costs, trimming, domain usage), the contradiction overrides any credit, per the rubric.

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 long, but every sentence adds necessary context: replacement behavior, brand limits, domain importance, credit costs, runNow mechanics, inheritance of country/platform, and how to read findings. It is well-structured and front-loads the core purpose. It could be tightened slightly (e.g., condensing some details about the weekly digest), but it is not redundant or wasteful.

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?

For a complex configuration tool with no output schema, the description covers all required knowledge: what the watch is, how to set/stop it, limits (max 5), domain use, credit costing, runNow behavior, inheritance constraints, and how to read results via list_watch_findings. Nothing an agent needs to call this 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?

Schema description coverage is 100%, so baseline is 3. The description adds substantial meaning beyond the schema: it explains that competitors is the complete list (replacement semantics), that an empty array stops the watch and clears findings, that domain is required for Google Ads Transparency and disambiguates Meta pages, and that runNow triggers an immediate spend. These enrich parameter understanding significantly, warranting a top score.

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 and resource: 'Set (or STOP) this workspace's standing COMPETITOR WATCH — the weekly job that re-checks each named brand's ad libraries and reports what is NEW since last time.' It clearly distinguishes the tool as configuring the watch, not performing a one-off check, and points to list_watch_findings for reading results. It is unambiguous about the primary function.

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?

Explicit usage rules are provided: 'This REPLACES the whole watched list, it does not add to it — pass every brand you want watched, every time,' and 'Pass an EMPTY list to stop the watch entirely.' It also states when to use runNow, explains that country and platform mix are not settable here, and references the weekly digest email settings. These are clear directives that guide when and how to invoke the tool.

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