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

Annotations already declare mutation (readOnlyHint=false), idempotency, and non-destructiveness, so the bar is lower; the description still adds real value by disclosing patch-only semantics and the Pro gating on two fields. It does not say whether changes go live to visitors immediately or what the response contains, leaving a modest gap for a mutation tool.

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?

Two sentences, front-loaded with the verb and resource, then the editable surface, then the patch-semantics caveat and Pro caveat. The dense field enumeration earns its place by letting an agent map its intent to the right nesting level without opening the schema.

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 6-parameter mutation tool with deep nested objects and no output schema, the description covers the essentials: what is mutable, that updates are partial, and that two fields are plan-gated. It could go further on whether the site must already have a banner and what changes return, but nothing critical to invoking it correctly is missing.

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 83%, so the schema already carries most parameter meaning, including the Pro notes on geo_targeting/monthly_rescan and the preset hint. The description's field list (layout values, categories, services, GCM v2, languages, wording) largely restates what the schema enumerates and adds no format or constraint detail beyond it. 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?

Starts with a specific verb+resource ('Update a site's cookie banner') and enumerates exactly which banner aspects can be changed (layout, colours/preset, categories, services, GCM v2, languages, wording). This makes it clearly distinguishable from read-oriented siblings like get_site, list_banner_presets, and run_compliance_scan.

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?

'Only the fields you pass change' establishes partial-update semantics, which tells the agent it can call this repeatedly with narrow payloads rather than sending a full object. 'Pro sites can also switch geo-targeting and monthly rescans' flags a plan eligibility condition. It stops short of naming alternatives (e.g. use list_banner_presets to obtain valid preset values), so no explicit when-not guidance.

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