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

While the description gives rich behavioral context (return shape, 'connected' boolean, email free-form nature), the annotation readOnlyHint=false contradicts the read-only implication of 'List every destination.' This is a clear contradiction between the described behavior and the structured metadata, so the score is 1 per rubric.

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?

The description is well-structured and every sentence earns its place: purpose, return format, usage instruction, and an example. It is not overly verbose and front-loads the core purpose.

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?

With no output schema, the description fully explains the return object (slack/teams/email structure, channel arrays, 'connected' boolean) and how to use the results to resolve channelId. This is complete for a listing tool, covering all necessary aspects.

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?

The input schema already covers the single optional 'slug' parameter 100%, including its auto-detect behavior. The tool description adds no extra details about the parameter, so the baseline of 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?

The description uses the specific verb 'List' targeting the resource 'every destination the organization can deliver reports or alerts to,' which clearly distinguishes it from siblings like create_report and create_alert. It also outlines the return structure keyed by provider, reinforcing the tool's scope.

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?

It explicitly instructs to call this tool before create_report or create_alert to resolve channelId values, and for email destinations to ask the user directly. This provides clear when-to-use guidance and a concrete example (the '#infra-costs' case), leaving little ambiguity.

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