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

Annotations already declare destructiveHint=true and idempotentHint=true, so safety is covered. The description adds genuinely non-obvious behavior: a domain already emailed by the site stays uncontactable and only its subdomains are unblocked. That is high-value context beyond annotations, though reversibility of the operation itself is not spelled out.

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?

Three short sentences with no filler, and the core action is front-loaded before the caveat and the limit.

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 destructive, idempotent mutation with no output schema, the description covers the action, sourcing rule, partial-effect caveat, and batch limit. Return behavior is unspecified, but that is a minor gap given the annotation coverage.

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 baseline is 3, but the description adds the batch ceiling of 100 domains per call, which is not present in the schema, plus the sourcing rule for the domains array.

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 ('Remove domains from the blocklist') and immediately scopes it against the sibling list_blocklist by requiring its exact text. An agent can distinguish this from block_domains and list_blocklist without opening a schema.

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?

Clearly signals the workflow (use the exact domain text that list_blocklist returns) and states a per-call cap of 100. It does not explicitly name block_domains as the inverse or describe preconditions, but the context is clear.

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