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

The annotations mark this as non-read-only yet idempotent and non-destructive, and the description explains why: the call can mint a fresh 24-hour nonce as a side effect while remaining repeatable, and it reaches out to /.well-known/ URLs (matching openWorldHint). That is genuine added context beyond the structured hints; it stops short of describing failure modes or how many attempts/polls are expected.

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 dense sentences, front-loaded with the action and followed by the return behavior. The /.well-known path names are jargon but each one carries information; nothing is padding.

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 one-parameter tool with no output schema, the description covers the return shape (verification result or new nonce) and the mechanisms used. Missing pieces are preconditions and failure behavior, which matter for a challenge/response flow but are less critical than the mechanics already given.

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?

There is a single parameter with 100% schema description coverage, so the schema already carries the burden. The description adds nothing about how agent_key is used or whether it must match the key used for the nonce challenge, so the baseline 3 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 names a specific verb (verify) and resource (endpoint ownership), and it distinguishes itself from agent_endpoint_set by being the verification half of the pair. It does not, however, explain how the two paths relate (well-known file vs. nonce challenge) or which one an agent should expect.

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?

Usage is implied rather than stated: the mention of a nonce and the required agent_key from agent_register hint that this runs after registration/endpoint setup, but there is no explicit call-this-after-X instruction and no comparison to the similarly-named sibling agent_contact_verify.

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