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

Annotations already declare readOnlyHint=false, openWorldHint=false, destructiveHint=false, so the agent knows this mutates local state without external side effects. The description adds that the effect is a do-not-email list entry plus a required reason, but omits the crucial behavioral facts: whether suppression is reversible, whether it stops in-flight outreach sequences, and how project vs global scope changes the blast radius.

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 with no filler or repetition. It is efficient, though the brevity is partly a symptom of under-specification rather than disciplined editing.

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 6-parameter, 5-required state-changing tool with no output schema and 0% schema coverage, one sentence is far too thin. An agent cannot determine scope semantics, valid reasons/sources, or the consequences of suppression from this definition alone.

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 0% across 6 parameters, so the description carries the full burden and fails. It mentions only 'reason' and the contact implicitly; scope (project vs global), source (manual/unsubscribe/bounce/complaint/platform_policy), and projectId/siteId are entirely undefined anywhere.

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 action and target: add a contact to the do-not-email list. That distinguishes it from create_contact, verify_contact, and the outreach-sending siblings, though it never names an alternative. The title adds the plain-language framing ('Stop emailing a contact').

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 statement of when to use this versus verify_contact, stop_outreach_sequence, or reject_prospect, and no prerequisites (permissions, required project/site context). The only usage signal is the implied 'reason' requirement.

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