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

The description adds valuable behavioral context beyond annotations: it warns that changing the subdomain 'changes the live URL — existing links will break' and notes that password protection requires a 'Lite+ plan'. These are side effects and prerequisites not captured in annotations. Annotations already declare idempotentHint=true and destructiveHint=false, so the description does not contradict them and provides supplementary detail.

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?

The description is a single, efficient sentence that front-loads the action and lists the mutable fields. Every clause adds value: the field list informs what can be updated, and the omission note clarifies behavior. There is zero redundancy or 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?

Given the output schema exists and annotations cover idempotency and non-destructiveness, the description covers the key context: side effects (subdomain change) and a prerequisite (Lite+ plan). It does not mention error handling or the behavior for invalid site_ids, but these are likely standard and not essential for correct invocation. The description is sufficiently complete for an agent to use it correctly.

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 every parameter has a description in the schema. The description adds a general note about omitting fields to leave them unchanged, which clarifies the update semantics but does not add per-parameter detail beyond the schema. This is adequate but not exceptional; baseline 3 is appropriate.

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 clearly states the tool's purpose: 'Update a site's metadata' and enumerates the specific fields (title, subdomain, description, password protection, homepage file). This differentiates it from sibling tools like create_site and delete_site. The verb-resource pairing is explicit and unambiguous.

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?

The description implies usage (updating an existing site) but does not explicitly state when to choose this tool over alternatives like create_site or delete_site. It provides a useful operational note ('Omit any field to leave it unchanged') but lacks explicit exclusions or comparisons to siblings. The context is clear enough for an agent to infer, but it stops short of explicit guidance.

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