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

'replacing what was there' explicitly confirms the destructive overwrite that the destructiveHint annotation only implies, and the send-resolution rule (single send vs. multiple A/B sends) is real behavioral context not present in the annotations. It stops short of saying what happens on a non-draft campaign or whether prior content is recoverable.

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 short clauses with the write/mutation warning front-loaded, then the parameter rule, then the endpoint as trailing reference. Zero 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?

For a 4-param destructive write with full schema coverage, rich annotations, and no output schema, this covers the essentials: mutability, overwrite semantics, and send targeting. The remaining gap is the draft-only precondition, which lives in the title rather than the description.

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 100%, so the baseline is 3; the description earns an extra point by explaining the semantics of send_id beyond the schema's terse 'Optional when the campaign has one send' — namely that A/B campaigns have several sends and you must pick one. html/text are left to their schema descriptions.

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?

Opens with a specific verb+resource ('set the HTML (and optional plain-text) content of an email campaign's send') and adds the critical qualifier that it replaces existing content. It also distinguishes itself from read-side siblings like sarbacane_get_campaign by prefixing 'WRITE:' and giving the underlying POST path.

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?

Gives a concrete condition for the tricky parameter: omit send_id when the campaign has one send, but pass one for A/B test campaigns. It does not cover when to prefer this over the sibling sarbacane_import_campaign_template, nor does it state the campaign must be a draft (only the title hints at that).

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