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

Annotations already establish this as a non-read-only, non-destructive, idempotent operation. The description adds useful behavioral context: the scheduled slot is preserved, in-flight sends are refused with DRAFT_ALREADY_DISPATCHING, and non-scheduled entries are refused with DRAFT_NOT_SCHEDULED. No contradiction with annotations appears.

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 with no filler: the first states the operation and key preservation guarantee, the second explains content shape, and the third covers failure modes and source of valid entries. Everything earns its place.

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, the description covers what is edited, what is preserved, when it fails, and how to locate eligible entries. There is no output schema, but the success path is simple enough not to require a return-value breakdown. A minor gap is not describing a success response or exact contents of updatedContent beyond { messageText }.

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 input schema has zero descriptions, but the description clarifies the otherwise-opaque updatedContent object by referencing the content shape of campaignstack_edit_and_approve_review and giving { messageText } as an example. entryId and workspaceId are left to be inferred from their names and the description context, which is acceptable though not explicit.

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 and resource: 'Change the text of an approved message that is still waiting at its send node, keeping its scheduled slot.' It clearly distinguishes this from related tools like campaignstack_edit_and_approve_review by emphasizing the scheduled, already-approved state and slot preservation.

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 explicit applicability conditions: the message must be approved and still waiting at its send node. It names the content-shape reference tool, describes when the tool refuses (in-flight send or non-scheduled entry), and points to where valid entries come from, giving an agent clear routing information.

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