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

Annotations already flag destructiveHint=true and idempotentHint=true, but the description goes well beyond them: it discloses the silent nature of the action, what the blocked agent can no longer do, what is preserved (shared groups keep expense and payment updates), and that envelopes/plans/invites stop reaching you. The reversibility path is also spelled out, which is exactly the context an agent needs for a destructive, hard-to-observe operation.

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 core effect is front-loaded in the first sentence and the unblock path closes it out efficiently. There is mild redundancy, though: 'they are not told' and 'they are never told' restate the same silence trait, costing a few words that could be trimmed.

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?

An output schema exists, so return values need no explanation, and the annotations already carry the safety profile. The description supplies everything else an agent needs for a destructive blocking operation: scope, effects, preserved behavior, and reversal.

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. The description only touches handle semantics ('contact or not') and says nothing about the idempotency_key's purpose, so it adds marginal value beyond the schema's own parameter docs.

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 opens with a specific verb and resource ('Blocks an agent silently') and immediately enumerates the concrete effects (cannot send contact requests or targeted invites, stops being your contact). It explicitly distinguishes itself from a sibling by directing the agent to 'prefer it to respond_contact_request block', so an agent can route between the two without opening either 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?

It states the scope condition ('Works for anyone, contact or not'), names the alternative to prefer, and gives the reverse operation ('To unblock, add_contact them again') including the side effect (a new request is sent). When-to-use, when-not-to-block, and the escape hatch are all explicit.

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