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

The annotations already declare readOnly, idempotent, non-destructive, and closed-world; the description confirms this with 'opens nothing by itself,' which is useful corroboration and tells the agent it must chain browser calls. However, the long paragraph about Discord's official API and the absence of an official MCP server is justification rather than actionable behavior, and no detail is given on the shape or length of the returned instructions beyond 'screens, buttons, fields.'

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 operative content is front-loaded and dense, but the final sentence about Discord's official API, including a dated 'checked 5 Nov 2026' claim, does not help an agent decide or invoke and pads the definition. Sentence length and stacked clauses make it harder to scan than it needs to be.

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 zero-parameter guide tool with no output schema, the description covers what is returned (step-by-step screens, buttons, fields), that no side effect occurs, and which tool family executes the steps. It could note prerequisites such as an existing browser session, but nothing essential is missing.

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 tool takes zero parameters, so the schema already covers everything and there is nothing for the description to disambiguate. Baseline 4 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 states a specific verb and resource (read the user's Discord mentions) and immediately clarifies that the tool actually returns step-by-step UI instructions rather than performing the read, which sets it apart from data-returning siblings like discord_read_channel_messages. The residual tension between the name 'read_mentions' and the actual 'returns a guide' behavior keeps it below a 5.

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 does give a follow-on path ('then do it with the cotlet_browser_* tools in the user's Discord Cloud Browser'), but it never states when to prefer this over cotlet_app_guide or the direct discord_* read tools. Usage is implied rather than explicitly routed.

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