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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutation profile is covered. The description adds real value with 'Blocking signs them out everywhere', a side effect not encoded in structured fields. It stops short of saying whether blocking also prevents future sign-in, whether unblocking restores access, or whether existing sessions are recoverable.

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?

Two short sentences, zero filler, with the action front-loaded and the consequence immediately after. Nothing could be cut without losing meaning.

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, non-read-only mutation with 33% schema coverage and no output schema, the definition is thin. An agent still lacks the unblock mechanism, the reversibility of the block, permission requirements, and the distinction from remove_visitor.

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?

Only one of three parameters (site) is documented in the schema, so coverage is 33% and the description should compensate. It instead names no parameter: it never explains that email identifies the target visitor or that blocked=false is the unblock path, leaving the default-true boolean to be guessed.

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 uses specific verbs (block/unblock) on a specific resource (a visitor), and states one concrete consequence. It does not, however, distinguish this reversible block from the sibling remove_visitor or from invite_visitor/list_visitors, so an agent must infer which visitor-lifecycle tool applies.

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 phrase 'block or unblock' implies one tool handles both directions, which is useful usage signal. But there is no statement of when to prefer this over remove_visitor, no prerequisite or permission note, and no guidance on how to effect an unblock (presumably blocked=false, which is never stated).

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