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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the description's job is to add behavior beyond that. Instead it mostly restates the parameter list from the schema: it never warns that routing_rules and geo_restriction are wholesale replacements, never confirms that omitted fields are left untouched, and says nothing about permissions or Pro+ gating consequences.

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 front-loaded sentence with the verb and resource first and the mutable fields following; no filler, no restated title, nothing that could be cut without losing information.

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 10 parameters, nested objects, a required short_code, no output schema, and a destructive annotation, the definition should say more about partial-update and replace-vs-merge semantics. The schema covers per-field details and the null-to-remove conventions, so the description is not inadequate, but it leaves a real gap for a destructive mutation 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 description coverage is 100%, so the baseline is 3. The description adds a useful framing that this is a partial-field update ("change destination, expiry, ..."), but it does not add syntax, format, or interaction semantics beyond what each schema property description already provides.

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 gives a specific verb and resource ("Update an existing short link") plus an enumeration of the mutable fields, which makes it clearly distinct from create/shorten operations in the sibling list. It stops short of naming any sibling tool (e.g. delete_link, get_link) as an alternative, so it lands at 4 rather than 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?

Usage is only implied by the verb "update" — an agent can infer this modifies an existing link rather than creating one, but there is no explicit when-not guidance, no mention of how it relates to delete_link or shorten_url, and no statement about partial-update behavior (what happens to fields that are omitted).

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