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

Goes well beyond the annotations, which only flag destructive/idempotent/openWorld. It discloses that only PNTR can write the name, that one value per subdomain replaces the previous value, that the record expires after 7 days or on subdomain delete/disable, and that GitHub sign-in is required.

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?

A single dense paragraph that front-loads the action, then the condition, the alternative to avoid, and the prerequisites/lifecycle. Every sentence carries distinct operational information; nothing is repeated from the schema or annotations.

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 two-parameter mutation with no output schema, it covers the trigger, the exclusion, prerequisites, value format, replacement semantics, expiry/cleanup behavior, and auth requirement. An agent has everything needed to call it correctly and knows why it might fail.

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%, so the baseline is 3; the description earns an extra point by adding a correctness constraint the schema does not state — the value must name that subdomain exactly, with the literal vc-domain-verify=<name>.pntr.dev,<code> shape and a one-value-per-subdomain cardinality rule.

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: publish the Vercel ownership TXT value for one of your subdomains. It also names the exact DNS name it writes (_vercel.pntr.dev), which disambiguates it from the generic DNS siblings without needing to open 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?

Gives the precise triggering condition (Vercel reports the domain linked to another account and asks for a TXT at _vercel.pntr.dev) and an explicit negative instruction: do not use add_dns_record for this name. It also states the prerequisite that the subdomain must already point at Vercel.

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