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

Annotations already give idempotentHint=true and destructiveHint=false, but the description adds real substance: omitted steps are removed (whole-sequence overwrite semantics), the idempotency rationale ("same payload twice leaves the same result, so a retry cannot duplicate steps"), and the effect on a live campaign (future sends change, already-sent emails are untouched). This is exactly the behavioral context annotations cannot convey.

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?

Four tight sentences, each carrying distinct information, with the destructive whole-replacement semantics front-loaded. No filler, though the idempotency and running-campaign points could be slightly compressed.

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, the description covers the critical decision points: it is a full overwrite, retries are safe, and live-campaign edits affect only future sends. Combined with 100%-covered schema and safety annotations, an agent has everything needed to call it correctly.

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% and the schema already documents id, steps, signature, delayDays, variants, etc. in detail. The description's "send the full sequence" reiterates what the schema already states ("The full sequence, first email first"), so it adds little parameter-level meaning beyond the structured data. Baseline 3.

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?

States a specific verb (replaces) and resource (a campaign's WHOLE sequence) with emphasis on the whole-vs-partial distinction. An agent can immediately tell this apart from update_campaign (field edits) and get_campaign_sequence (read). No ambiguity about what the tool does.

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?

"This is not a partial edit: steps you leave out are removed, so send the full sequence every time" gives clear usage context and implicitly steers away from incremental-edit assumptions. It stops short of naming the sibling alternative (e.g. update_campaign) or stating preconditions like the campaign needing to exist, so it is strong but not exhaustive.

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