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

Annotations establish readOnlyHint=false and idempotentHint=true. The description adds traits beyond annotations: subdomain coverage ('each covers its subdomains'), a rate limit ('Up to 500 per call'), and an important safety reassurance ('Sends nothing'), which tells the agent no outreach is triggered. Missing detail on reversibility or return behavior, but the additions are substantive.

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?

Four tight fragments with zero waste. The verb and object are front-loaded, and behavioral facts (subdomains, 500 limit, 'Sends nothing') follow in order of importance.

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 write tool with no output schema, the description covers scope, capacity, format and side effects adequately. It lacks explicit undo/reversibility guidance and any pointer to unblock_domains, but is otherwise sufficient to call 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 coverage is 100%, so the baseline is 3. The description still adds meaning beyond the schema: 'Bare domains or URLs' clarifies accepted input format and 'each covers its subdomains' documents scope behavior the schema does not.

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: 'Add domains outreach must never contact.' An agent can tell it adds to a blocklist rather than removing. Sibling differentiation from unblock_domains/list_blocklist is only implicit via the opposite verb, not explicitly named.

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 usage context via examples (competitor, partner, client), which implies when to use it. However it never names the alternative unblock_domains or states when NOT to use this tool, leaving routing to inference.

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