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

Annotations only signal destructiveHint=true; the description goes further by disclosing that deletion is permanent, exactly which data classes are destroyed (events, session replays, profile), and that a write key plus admin access are required. That is meaningful added context for an irreversible mutation.

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?

Two short sentences, with the destructive scope front-loaded in the first clause and prerequisites second. No filler or repetition of the tool name.

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 2-parameter, no-output-schema tool, the description covers irreversibility, data scope, and authorization needs. It leaves open whether the deletion is synchronous or how confirmation of completion is surfaced, a minor gap given the tool's simplicity.

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% and already documents both site_id (from list_sites) and the user_id / 'anon:<visitor_id>' format. The description adds no parameter-level detail beyond what the schema provides, so the baseline 3 applies.

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 ('permanently delete ... events, session replays and the profile of one user on a site') and enumerates the exact scope of deletion. This clearly distinguishes it from read-oriented siblings like get_user and list_users.

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?

Framing it as 'GDPR erasure' gives clear context for when to reach for this tool (compliance deletion for a single user), and it states the access prerequisites. It does not name an alternative or state when not to use it, so it stops short of explicit routing guidance.

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