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

The description discloses meaningful behavior beyond the annotations: it reads the post from X, takes the author as the linked account, requires the post to be proof, and explains the success outcome. It also states the Authorization header requirement and that the handle gets stamped and posts begin earning seeds.

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 dense but efficient: it front-loads the core action, then explains the proof requirement, the effect, and the auth need. Each sentence contributes necessary information without redundancy.

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 one well-documented parameter and no output schema, the description covers everything an agent needs: what input to provide, where it comes from, the validity conditions, the outcome, and the required auth. It is fully adequate for correct invocation.

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 schema already documents the single parameter well at 100% coverage. The description adds semantic weight by explaining the parameter must be the post carrying the nonce from x_link_start, and that the post serves as proof, which goes beyond the schema's basic type description.

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 clearly states the tool's function: it finishes a headless X link verification by taking the author of a posted nonce as the linked account. It explicitly references x_link_start, distinguishing this as the second step in a two-step flow.

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?

The description tells the agent to supply the post id or link carrying the nonce from x_link_start, and specifies the key requirements: the post must be published from the claimed account and post-date the challenge. It lacks an explicit when-not-to-use statement, but the intended usage context is clear.

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