Who competes for the same keywords

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

With only generic annotations (readOnlyHint=false, destructiveHint=false), the description adds meaningful behavioral context: it costs credits, cached results are free, and domains already looked up via research_domain_overview are free. It also tells the agent that results indicate whether a full growth report already exists. This goes beyond the schema and annotations, though it does not discuss auth or other side effects.

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 three sentences that front-load the output definition, then give usage guidance, then cost/caching behavior. Every sentence adds distinct value with no filler or repetition of the schema.

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 one-parameter tool with no output schema, the description covers the output fields, the use case, cost behavior, and the follow-up path to read_report. It is sufficiently complete for an agent to invoke and interpret the tool 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?

The schema already provides 100% coverage for the single `domain` parameter with an example ('notion.so'). The description only refers to it as the 'target' and does not add new formats, constraints, or meaning beyond what the schema communicates, so baseline 3 is appropriate.

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 clearly identifies the resource: 'domains fighting a target for the same search terms,' and lists the exact output fields (shared-keyword count, keyword totals, average rank). This distinguishes it from siblings like research_domain_overview and research_backlinks.

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 explicitly states when to use the tool: 'Use when the user asks who their competitors are, or who a company is up against.' It also offers a clear alternative by telling the agent to use read_report for existing growth reports instead. It does not enumerate exclusions for every sibling, but the context is strong.

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