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

Annotations only declare readOnlyHint=false, destructiveHint=false and openWorldHint=false. The description goes well beyond that by disclosing the two-phase confirm-then-commit protocol, the confirmation_required response, and a specific refusal path (name_detected_pending_confirmation) with a nextStep. It could still say what a successful call returns, which matters because there is no output schema.

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 dense sentences with the core action first, then the confirmation precondition, then the failure mode. Every clause carries information, and no wording is wasted or redundant.

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 seven-parameter mutation tool with no output schema, the description covers the write's side effects, the confirmation gate, and the main error path. The remaining gap, the shape of a successful response, is minor given that the schema fully documents the inputs.

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 baseline would be 3, but the description adds real meaning: it explains that text and prompt are the same rule expressed two ways, and that naming someone absent from mentions is refused. expiresAt and confirmedGeneralScope are not discussed in the description but are adequately documented in the schema.

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: 'Adds a screening rule for the user's incoming calls', then enumerates the rule's components (text, prompt, emoji, mentions). It is clear what the tool creates, but it never contrasts itself with the sibling update_rule or list_rules, so an agent must infer that this is the creation path rather than a modification path.

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 gives concrete usage conditions around the write: without confirmed:true nothing is added and a confirmation_required preview is returned with the exact rule. That tells an agent how to call it safely. It stops short of explicit when-to-use guidance versus update_rule or delete_rule, or prerequisites like whether the user must be authenticated.

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