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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=false, so the destruction signal is carried structurally. The description adds real value beyond that by naming the blast radius: events remain tracked but stop reaching automations. It does not say whether the erasure is reversible or what is retained, which leaves a gap for a destructive privacy 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?

A single sentence with purpose and effect front-loaded and no filler. Every clause earns its place.

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 one-parameter, no-output-schema tool with annotations covering safety, the description gives enough to invoke it correctly. The main omission is what happens to events already recorded and whether errors occur for unknown user_ids.

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 baseline is 3. The description goes slightly beyond by explaining that the user_id is the lookup key for the phone number being forgotten, which disambiguates the schema's thin 'Your user id' hint. It still does not state whether user_id must be an existing, previously-seen identity.

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+resource (forget/erase the phone number linked to a user_id) plus the downstream effect. This is clearly distinguishable from delete_contact or redact_message in intent, though no sibling is named explicitly. An agent can tell what the tool does without opening the 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?

The 'Privacy erasure' framing and the consequence (tracked events stop reaching automations) imply the use case: honoring an erasure request. However, no explicit when-to-use/when-not, no prerequisites (e.g., does the user need to exist?), and no named alternative such as delete_contact for full record removal.

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