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

Annotations already declare readOnlyHint=true, so safety is covered; the description adds real context beyond that — the return payload shape, the account/auth requirement, and the non-obvious constraint that a link shown only in a tool result is one the user never saw. It omits polling semantics or whether repeated calls mutate the verification state.

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?

Front-loaded with the purpose and return contents, then the user-visibility caveat, then access. The middle paragraph is longer than strictly needed, and the closing 'start_login does NOT open this tool' is slightly tangential, but every section carries useful information.

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 no output schema, the description compensates by describing the returned fields, and it covers the auth prerequisite and the user-visible-output constraint. For a single-ID read tool this is nearly complete; only pagination/retry or freshness behavior is unaddressed, which is minor here.

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 100% and the single parameter (id, 'Verification ID') is fully documented in the schema. The description adds only the phrase 'by ID', which adds no syntax or format detail beyond what the schema provides, so 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?

States a specific verb and resource ('Get a verification by ID') and enumerates what the returned object contains (status, channel, proof token if verified). It does not, however, differentiate itself from near-siblings like get_verification_request, get_multi_channel_verification_status, or get_proof_status, so an agent still has to infer which of these retrieves which resource.

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?

Gives a concrete precondition for calling it: before invoking on a challenge you created, your reply text must already surface the link/SMS/inbox instruction to the user. It also flags the authentication prerequisite. It never names an alternative tool or states when-not to use it, so it stops short of full routing guidance.

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