Backlink lookup

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint. The description adds useful behavioral context: the data source (Common Crawl webgraph) and quota/cost details, which go beyond annotations. No contradiction with annotations.

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, front-loaded with the main action 'Look up referring domains'. It is concise, avoids fluff, and covers key aspects: action, outputs, source, and cost.

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?

The description covers purpose, outputs, data source, and quota, and the schema and annotations handle parameters and safety. It is mostly complete, though it could optionally mention error handling or behavior for missing domains.

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 the schema already explains each parameter. The description adds minor context (data source, quota) but does not significantly enhance parameter understanding beyond what the schema provides. 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 states the tool looks up referring domains (backlinks) for a single target domain, specifying the returned data (linking domain, host count, authority score, target authority/rank). This distinguishes it from sibling tools like gap_analysis and gap_outreach_targets, which serve different purposes.

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?

The description mentions the cost (one backlinks call against monthly quota), giving context on usage limits. However, it does not explicitly state when not to use or offer direct alternatives, though the context implies it's for obtaining backlink data.

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