update_site_custom_code

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

Annotations only declare readOnlyHint=false, so the description carries most of the burden. It adds genuinely useful behavior beyond that: the merge semantics (unspecified fields are left unchanged) and a mandatory read-then-confirm approval workflow. It stops short of covering failure modes, auth/permission requirements, or publish timing.

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?

Front-loaded with the operation and the critical approval constraint before the per-field list, so the most important guidance is not buried. The bullet list is compact and each entry earns its place, though the repeated field mapping slightly overlaps 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 mutation tool with no output schema and full parameter coverage, the definition supplies the essential workflow, merge semantics, and field semantics. It omits error behavior and whether changes take effect immediately, which are minor for this operation type.

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 coverage is already 100%, so the baseline is 3. The description adds real meaning over the schema by noting code_custom_css is auto-wrapped in <style> and clarifying insertion points (before </head> / before </body>), which the terse schema strings do not convey.

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 custom code (CSS/JS) for the entire site') and clarifies the mutation is partial ('Only sends fields you specify — others remain unchanged'). It names the read sibling get_site_custom_code as a prerequisite, but never distinguishes itself from the write sibling append_site_custom_code, which an agent could easily confuse it with.

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?

Explicit and forceful about when and how to use it: it MUST be preceded by get_site_custom_code, the user must be shown the diff, and explicit confirmation must be obtained before updating. The alternative read tool is named and the pre-condition is spelled out, leaving nothing to inference.

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