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

The description adds real context beyond annotations: no email is sent and ownership confirmation is a prerequisite. However, the annotations declare destructiveHint=true, and the description never addresses whether verification can be undone, whether it grants access, or how the change propagates to the source system. Reasonable addition, but it leaves the most consequential behavior unexplained.

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 short sentences, zero filler, with the core action front-loaded and the clarifying parenthetical placed inline where the reader needs it.

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 single-parameter tool with full schema coverage, annotations, and no output schema, the description covers what it does, the precondition, and the key 'no email sent' distinction. It is only thin on the consequences of a destructive-flavored state change.

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 coverage is 100% and the user_id field already documents the preferred app id versus the VibeAdmin id from list_users. The description adds no further meaning about identifier resolution or error behavior, so the baseline 3 is appropriate.

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 (mark the email as verified) plus the scope where the change happens (the source system). The parenthetical '(it does not send an email)' actively distinguishes it from adjacent siblings like send_email and send_password_reset, so an agent can choose without opening the schema.

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 sentence 'Use after you have confirmed they own the address' gives an explicit precondition for invocation, which is genuinely useful for a security-relevant state change. It stops short of naming alternatives or stating when not to use it (e.g., already-verified users), so it does not reach the top band.

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