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

Adds real behavior beyond annotations: the return is a link the user must open in a browser, the connection only materializes after the user completes the flow, and the call "may wait for the owner's confirmation." This explains why a get-style tool is annotated as not read-only, which the annotations alone would leave confusing.

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?

Four short sentences with the return value front-loaded. The final sentence lightly restates the title's intent but doubles as usage routing, so waste is minimal.

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?

Covers what is returned, what the agent/user must do with it, and the asynchronous confirmation caveat. Without an output schema, it could say a bit more about the link itself (expiry, single use) or what the agent should do if the wait times out.

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?

Zero parameters, so the baseline of 4 applies; there is nothing for the description to disambiguate and no misleading parameter talk.

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?

Specific verb and resource: "Returns a Threads OAuth link for the user to open in a browser to connect a new Threads account." It explicitly positions itself relative to list_accounts (where the result appears), so an agent can distinguish it from sibling listing/reading tools.

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?

States the triggering condition clearly ("Applies when the user wants to add an account") and references the follow-up flow ending in list_accounts. It doesn't name an alternative tool for the case where the user already has an account connected, but the positive condition is unambiguous.

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