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

Goes well beyond the annotations: states the 10-rival cap, the idempotent dedup rule, that the call is free, that it requires the 'act' scope, and what the response contains. The destructiveHint=true annotation is not contradicted by the text, which describes an additive write with existing entries preserved.

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 action, then explicitly partitioned into WHEN and WHAT COMES BACK sections. Every clause carries information (precondition, limit, dedup, cost, scope, return) with no 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?

Despite having no output schema, the description compensates by describing the return value ("the roster, the new rival marked"). Combined with the limits, auth scope, and dedup behavior, an agent has everything needed to call this correctly.

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 both 'domain' and the optional 'name' are already documented, including the default-to-domain behavior. The description adds only the dedup matching semantics ("by domain or by name"), so the baseline of 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 (add), a specific resource (one company/rival), and its downstream effect (measured by the next AI visibility scan and carried by every competitor read). It is clearly distinguishable from the read-side sibling get_competitors, which only lists the roster.

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 an explicit gating precondition ("only after they say yes to that rival") and handles the duplicate case ("a rival already on the roster, by domain or by name, is left as it is"). It does not name a sibling alternative such as get_competitors for the read case, so it falls short of a full when/when-not/alternative treatment.

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