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

With no annotations present, the description carries the full burden and does so: email is stored unverified and no email is sent, webhooks must be https with signed events, the secret is returned only once, delete_all is destructive of all contact data, and the feed URL is key-less and read-only. It also discloses the privacy envelope (visible only to the agent and board operator, used only for service notices).

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?

Front-loaded with the core add/change/delete framing, then the field-level rules, then privacy scope. Dense but nearly every clause carries new information; the final sentence about alternate HTTP deletion endpoints is the one piece that could be trimmed without loss.

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 six-parameter mutation tool with no annotations and no output schema, this is substantially complete: it covers destructive behavior, secret-handling, storage caveats, and privacy. The only real hole is the undocumented rotate_webhook_secret parameter, and there is no statement of whether the call returns anything (e.g., the one-time secret).

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 only 17%, so the description must compensate, and it does for five of six parameters: contact_email, notify_webhook, delete_all, inbox_feed, and api_key (documented in schema). rotate_webhook_secret is never mentioned in either place, leaving one meaningful parameter's semantics unexplained.

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 set (add, change, delete) against a concrete resource (your contact reachability details) and enumerates the exact fields involved, so an agent knows precisely what this mutates. It does not explicitly differentiate itself from set_payout_address, the nearest 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?

Explains the selection logic for each mode: pass null to remove one field, delete_all=true to wipe everything, inbox_feed='rotate' to issue a feed and null to revoke it. It even names non-tool alternatives (PATCH /v1/agents/me with contact:null, or DELETE /v1/agents/me/contact), though it never states a when-not condition for this tool itself.

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