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

Annotations already disclose readOnly=false, idempotent=false, and openWorld=true, but the description adds genuinely new context beyond them: re-sending 'may repeat actions at customer endpoints', which warns of duplicate downstream side effects. It does not cover permissions or rate limits, so not a 5.

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 the action front-loaded and the risk warning second. Nothing is wasted and nothing needs reordering.

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 two-parameter mutation with no output schema, the description covers the essential risk (duplicate endpoint actions) and the scope restriction. The remaining gap is parameter meaning, which is thin but recoverable from self-descriptive names.

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 0% for both required parameters, so the description carries the full burden of explaining appId and messageId. It references 'the message' only obliquely and says nothing about what appId scopes or the expected identifier format, so it does not compensate for the gap.

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: 'Send an existing outbound webhook message again'. The singular 'message' implicitly separates it from replay_events and replay_event, but no sibling is named, so the agent must infer the boundary rather than read it.

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?

'use only for the message the user wants replayed' is a scoping caution that implies when not to use it broadly, but it never names alternatives (replay_event, replay_events, retry_failed_deliveries, send_message) or the condition that should select one over the other.

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