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

Annotations already declare non-read-only, idempotent, non-destructive, open-world behavior. The description adds genuinely new operational context beyond that: printed QR codes follow the new destination within about a minute (a propagation delay the agent cannot infer from annotations) and the sign-in requirement. It says nothing about failure modes or what happens to untouched fields beyond 'pass only the fields to change'.

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?

Four short sentences, front-loaded with the mutation scope, followed by the side effect, the auth prerequisite, and the invocation rule. No sentence is redundant and nothing is buried.

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-resource partial-update tool with no output schema, the description covers scope, side effects on printed QR codes, auth requirement, and update semantics. An agent has everything needed to call it correctly and to set user expectations about latency.

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%, so the baseline is 3 and the schema already documents every field including the 404 behavior of disabled. The description adds real meaning on top: the partial-update rule ('pass only the fields to change') tells the agent omitted fields are left untouched, which the schema's absence of defaults does not make explicit.

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 (changes a Snip link) and enumerates the mutable dimensions: destination, title, enabled/disabled state. An agent can distinguish this from delete_link (removal) and shorten_link (creation) without opening any 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 clear context for use: it operates on one of the user's existing links, requires the user signed in to Snip, and instructs 'Pass only the fields to change', which defines the partial-update contract. It does not name an alternative tool or state when-not to use it, so it stops short of a 5.

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