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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description still adds real value beyond them: the required `message:edit` permission and the platform-imposed edit window that can cause the call to fail.

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 short sentences, with the action front-loaded and the permission/window constraints following. The only waste is the leading line duplicating the title verbatim.

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 mutation with no output schema and two undocumented required parameters, the description covers auth and timing but says nothing about error behavior when the edit window has closed or whether the prior content is lost. Adequate but with clear gaps.

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 two required parameters, so the description must carry the burden and largely fails to. It never mentions `messageId` or clarifies whether `content` replaces or appends to the existing body.

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 states a clear verb and resource ('Edits the message on the platform'), but the opening line 'Edit message' merely restates the title and name. It offers no differentiation from adjacent siblings like messages_unsend or messages_send, which also mutate an existing message.

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 gives two implicit usage conditions: the caller must hold the `message:edit` scope, and the edit must occur inside the platform's edit window. That is genuine when-to-use context, but there is no comparison to alternative tools for changing or retracting a message.

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