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

The description goes well past the annotations by disclosing a side effect the agent could not otherwise predict: colour, logo and position changes queue a rebuild, that rebuild is skipped (and reported) when the domain has hit its page-view limit, and text changes go live without one. It also states the merge semantics of the update, which matters given destructiveHint=true. The annotations already flag the write/it is a write and destructive profile, so this added operational context is exactly the right supplement.

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 sentences, front-loaded with the purpose, then the partial-update rule, then the exclusions and the rebuild caveat. The final sentence carries a dense parenthetical about the page-view limit, but it is genuinely load-bearing information rather than filler. Little could be cut without losing behaviour.

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 five-parameter nested mutation tool with an output schema present, the description covers what can change, what cannot, what happens to unspecified fields, and the asynchronous rebuild consequence with its failure condition. Nothing an agent needs to call it correctly and warn the user appropriately appears to be 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 100%, so the nested logo, texts, colors, domainId and positions objects are already documented in the schema, including locale format and per-language constraints. The description adds the meaningful nuance that texts are per-language copy for languages the banner already has and that category texts are out of scope, but it does not elaborate on field-level choices such as the position enums. 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?

"Changes how one of your CookiePal domains' banner looks and reads" gives a specific verb and resource, and the enumeration of modifiable facets (colours, logo type and colour, positions, per-language title/description/button texts) makes the scope concrete. It stops short of naming the closely related siblings (set_banner_mode, regenerate_banner), so the boundary against those is left to the agent to infer.

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?

"Give only what you want to change; everything else keeps its saved value" clearly frames this as a partial update, and the exclusion sentence routes logo uploads and category texts to the dashboard. What is missing is explicit routing against sibling tools that also touch banner state, so the agent must guess when to prefer set_banner_mode or regenerate_banner.

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