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

Annotations already cover readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile needs no restating. The description adds value by itemizing the sections of the returned reference (block format, rules, design rules, defaults, example), which effectively substitutes for the missing output schema; it stops short of saying what the payload format is (prose vs structured).

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?

A single sentence packs the return contents, the target tool, and the call-before-writing directive with no filler. The colon-separated content list is front-loaded and easy to scan.

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 parameterless read-only reference fetch with no output schema, the description supplies enough to know when to call it and roughly what comes back. A minor gap remains: it does not say whether the same format guidance applies to update_campaign_draft or template editing, or whether re-reading is ever required.

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?

The schema declares zero parameters, so there is nothing for the description to disambiguate. Baseline 4 applies.

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 enumerates what you get back (block format, draft rules, design rules, defaults, an example) and ties it explicitly to create_campaign_draft, which distinguishes it from siblings like render_email_preview or get_template. It never uses an explicit 'returns documentation' verb, so the action is inferred from a content list rather than stated outright.

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?

'Read it before writing blocks' gives a concrete trigger condition and names the downstream tool whose input it governs. There is no explicit exclusion (e.g. whether it is also needed for update_campaign_draft or templates), but the when-to-use signal is unambiguous.

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