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

Beyond the annotations (which only say it's a non-read-only, non-idempotent, non-destructive write), the description discloses pricing ($0.01 per call, free on failure), the random 7-character default, the irreversibility of code reuse after deletion, and that the destination is mutable. These are exactly the behavioral facts an agent can't get from structured fields.

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 tight sentences, front-loaded with the result and scope, then the alias decision, then lifecycle and cost caveats. Every clause carries actionable information with no filler.

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 adequately conveys what comes back (the short link itself) and covers cost, aliasing, and mutation/deletion semantics. It stops short of describing the rest of the response (e.g. an id, click count field, or whether URL is validated), which would fully close the loop for a create tool.

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, but the description adds real meaning for 'alias': it's optional, produces a readable slug when supplied, and falls back to a random code when omitted — context the schema's character-class note doesn't convey. The 'title' parameter is never mentioned, keeping it from a 5.

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 concretely states what gets produced (a cncto.co/<code> short link that redirects to url and counts clicks), which is far more specific than the name alone. It doesn't explicitly name the sibling tools (links_update/links_delete) it differs from, though the 'destination can be changed later' line hints at the update path, so it stops short of 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?

It gives concrete use cases — messages, print, QR codes — and explains the alias-vs-random decision with an example of each. What's missing is explicit routing to alternatives (e.g. when to use qr_create or links_update instead), so it's clear context without exclusions.

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