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

Annotations already mark this as readOnlyHint=false, destructiveHint=true, and idempotentHint=true. The description goes far beyond those: it discloses that it WRITES to configuration, deliberately POSTS a test message before saving, explains failure semantics (if post fails, nothing is saved and reason returned), requires confirmation, and notes the PRO plan requirement. It also explains that first-time binding uses defaults while subsequent changes keep settings. No contradictions with annotations.

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 long but every sentence carries functional weight: usage trigger, write target, cannot-do limitations, deliberate post behavior, failure handling, confirmation requirement, settings preservation, sibling pointer, and plan requirement. It's front-loaded with the primary purpose and then methodically covers constraints. Slightly verbose but not padded; a more compact version would risk losing nuance.

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 tool with three parameters, no output schema, and no nested objects, this description is exceptionally complete. It covers when to call, prerequisites (Slack connected, PRO plan), interaction flow (ask for channel, confirmation token), failure behavior, side effects, and relationship to a sibling. An agent would know exactly how to invoke this correctly and what to inform the user about.

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 100% and each parameter already has a clear description. The tool description adds meaningful context: channel names are passed exactly as given and will cause refusal if unreachable; the confirm token is a two-step flow with a 10-minute validity and single-use; website must be registered in Inclusify. This goes beyond the bare schema, though most of the parameter meaning is already in the schema.

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 opens with a clear, specific purpose: 'Use this when the user wants accessibility alerts for a site to go to a Slack channel, or to a different one than now.' It distinguishes itself from the sibling set_slack_events by explicitly stating it controls the destination, not the event types. It also clarifies the resource (Inclusify configuration, not the site) and the side effect (writes to config, posts to Slack).

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?

Provides explicit when-to-use guidance ('when the user wants accessibility alerts for a site to go to a Slack channel...') and clear exclusions: it cannot install Slack (must already be connected), cannot list channels (agent must ask the user), and requires confirmation. It also points to the alternative: 'Use set_slack_events to change which alerts fire.' This leaves no ambiguity about selection.

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