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

Annotations only declare write/non-destructive/non-idempotent; the description adds genuinely new traits: no payment, no account required, a human reads the message, and a rate limit of a few messages per hour. It stops short of saying what happens on rejection or whether the message is retained or published.

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 tight sentences with zero waste; the free/no-account framing is front-loaded before the behavioral caveats.

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 4-param write tool with no output schema, the description conveys cost, auth requirements, rate limits, and downstream human handling. It is nearly complete, missing only what the agent gets back or what happens if the rate limit is hit.

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 75% and the schema itself documents kind (enum), route, contact, and message. The description adds no format or semantic detail for any parameter — 'route' and 'contact' are never mentioned, and the kind list omits 'other'. Baseline 3 is appropriate when the schema does the heavy lifting.

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 (tell) and audience (the people who run this service) plus the content domain (bug, idea, thanks). No sibling tool (check_name, create_inbox, list_messages, etc.) competes for this intent, so an agent can route here unambiguously.

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?

Implies when to use it by enumerating the sendable content types ('a bug, an idea or a thanks'), which map onto the kind enum. It gives context (free, no account, rate limited) but never states when not to use it or points to an alternative channel.

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