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

Annotations declare the safety profile (destructiveHint=true, idempotentHint=true), and the description adds real substance beyond them: all of the contact's addresses are blocked, the lead is disqualified and deleted, deletion is recoverable within 30 days, and the card is refused with the block as the reason. This is exactly the destructive-scope context an agent needs.

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?

A single front-loaded sentence that states the action first, then enumerates its effects via a colon-delimited list. No filler, no restatement of the name, and every clause carries distinct information.

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 mutation with no output schema, the definition covers the action, the full side-effect chain, reversibility window, and the optional parameter's effect, while annotations carry the idempotency and safety signals. An agent has enough to invoke it correctly without further context.

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 schema alone justifies a baseline 3. The description goes further by explaining card_id's role (the card is refused, using the block as the refusal reason) and confirming that both contact addresses and the optional card are affected, adding meaning beyond the schema's terse field descriptions.

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 ("Block a lead's sender") and pins the semantics to a known product behavior ("as Flow's Block does"). The action is unambiguous and clearly distinct from unblock_a_sender, but the description never explicitly contrasts itself with that sibling, so it stops short of a 5.

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?

There is no explicit when-to-use or when-not-to-use statement and no named alternative such as unblock_a_sender. Usage is only implied through the described consequences (disqualification, deletion, card refusal), which the agent must reason about itself.

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