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

Annotations already declare write (readOnlyHint=false), idempotent, non-destructive, and closed-world. The description adds value on top: the idempotent reuse behavior is spelled out in operator terms, and two external constraints (own-site refusal, 50-competitor limit) are disclosed that annotations cannot convey. It doesn't say what a refusal looks like (error vs. silent no-op), which keeps it from a 5.

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?

Three tight sentences with zero filler, front-loaded on what the tool does before constraints, then a short related-tools pointer. Every sentence carries information an agent needs.

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 mutation semantics are covered by annotations plus the refusal rules in the text. The one small gap is the failure mode (what error or state results when your own site or the 50-cap is hit).

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% and both parameters are documented in-schema, including the default for 'name'. The description adds no syntax, format, or naming guidance beyond what the schema already states, so 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 and resource ('starts tracking a competitor's domain') plus the downstream effect (scorecard and AI answer matches), which goes beyond a bare restatement of the name. It explicitly names list_competitors and untrack_competitor as relatives, so an agent can place it among siblings without opening schemas.

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?

Gives concrete preconditions: re-tracking the same domain reuses the existing competitor, your own sites are refused, and a 50-competitor cap applies. It names related tools but does not explicitly route the agent ('call X when you want Y'), so it stops just short of full when/when-not guidance.

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