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

Annotations only declare readOnlyHint; the description adds non-obvious behavior — a platform with no auction data explains why rather than returning zeros, preventing an agent from misreading empty results as a competitive gap. It also discloses Space scoping and the per-call override. It does not cover data freshness or sync prerequisites.

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 resource and its metric list, then behavior, then scoping. The metric enumeration is dense but each item tells the agent what it will get; no filler sentences.

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?

With no output schema, the description carries the burden of describing returns and does so by naming the metric groups. The zero-result behavior note is a meaningful completeness win. Remaining gap is how to obtain a valid competitor_id and whether data depends on a recent sync.

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 both parameters are documented in structured fields and the baseline applies. The description's space_id override sentence mostly restates the schema, and it adds nothing about competitor_id — e.g., that IDs come from list_competitors.

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 (competitor auction data) and enumerates the exact metrics returned: overlap rate, outranking share, top-of-page rates, 13-week trend, impression share lost to rank. This clearly separates it from sibling read tools like get_competitor_coverage or get_competitor_offers, though it never names those siblings explicitly.

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?

Imparts clear context (auction/competitive overlap per platform) and gives actionable scoping guidance, naming set_active_space for switching and explaining the space_id one-call override. It stops short of stating when to prefer this over adjacent competitor tools such as get_competitor_coverage.

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