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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered; the description adds genuinely new context: the verification prerequisite, the Pro plan gating, and a pointer that billing is handled in the web dashboard. It stops short of explaining what activation destroys or displaces (e.g. existing link routing), which is the one thing the destructive flag would make an agent want.

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?

Three short sentences with zero waste: purpose first, then the hard prerequisite, then the plan requirement and billing note. Front-loaded and easy to scan.

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 mutation with no output schema, the description covers prerequisites and plan gating adequately, and annotations cover safety semantics. The remaining gap is what happens to the domain's existing links or state on activation, which a destructive operation could reasonably disclose.

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 single 'domain' parameter is already documented with an example, so the description adds little parameter-level meaning beyond reinforcing the 'verified' qualifier. Baseline 3 is appropriate when the schema carries the load.

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 with the effect ('starts serving short links'), and the prerequisite 'must already be verified' implicitly separates it from verify_domain and add_domain. It does not explicitly name those siblings, so a 4 rather than a 5.

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?

Provides prerequisites (domain already verified, Pro or higher plan) which tell the agent when the call is even legal, but gives no explicit guidance on when to activate versus verify_domain or update_domain, nor any note about deactivation or re-activation ordering.

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