Replace a scheduled message before it is sent; all required fields must be provided.
| Name | Required | Description | Default |
|---|---|---|---|
| cc | No | ||
| id | Yes | ||
| to | Yes | Recipient emails | |
| bcc | No | ||
| body | Yes | HTML | |
| subject | Yes | ||
| scheduled_at | No | Unix seconds | |
| from_account_id | No | Default: API key owner's default mail account | |
| reply_to_email_id | No | Mailbox message id to reply to | |
| send_in_new_thread | No | Send as a new thread |
Changes observed during successful MCP inspections.
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#"Input schema / additionalPropertiesRemoved value: -falseInput schema / properties / bcc / descriptionRemoved value: -"Blind carbon-copy recipient email addresses."Input schema / properties / body / descriptionPrevious value: -"Email body as HTML."New value: +"HTML"Input schema / properties / cc / descriptionRemoved value: -"Carbon-copy recipient email addresses."Input schema / properties / from_account_id / descriptionPrevious value: -"Sending mail account ID. If omitted, the API key owner's default mail account is used."New value: +"Default: API key owner's default mail account"Input schema / properties / id / descriptionRemoved value: -"Message ID."Input schema / properties / reply_to_email_id / descriptionPrevious value: -"Optional mailbox message ID to reply to."New value: +"Mailbox message id to reply to"Input schema / properties / scheduled_at / descriptionPrevious value: -"Updated send time as a Unix timestamp in seconds."New value: +"Unix seconds"Input schema / properties / send_in_new_thread / descriptionPrevious value: -"Whether to send the updated message as a new thread."New value: +"Send as a new thread"Input schema / properties / subject / descriptionRemoved value: -"Email subject line."Input schema / properties / to / descriptionPrevious value: -"Primary recipient email addresses."New value: +"Recipient emails"Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already indicate destructiveHint=true and readOnlyHint=false, so the description doesn't need to repeat that. It adds the timing constraint 'before it is sent', which is useful behavioral context. However, it doesn't disclose other behavioral aspects like what happens to the original message or if it's a full overwrite, though that's implied.
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?
The description is a single, concise sentence that immediately states the core purpose. It's front-loaded and contains no filler. Every word contributes.
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?
Given the tool has 10 parameters and no output schema, the description is too brief to be complete. It doesn't mention return values, error conditions, or any prerequisites. An agent would lack context on what to expect after calling it.
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 description provides no parameter-specific information beyond the schema. With schema coverage at 60%, four parameters (id, cc, bcc, subject) lack descriptions, and the description does not fill that gap. It only states that required fields must be provided, which is generic.
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 states the tool replaces a scheduled message before it is sent, which is specific and clear. It uses the verb 'replace' and identifies the resource as 'scheduled message', distinguishing it from generic update tools. However, it does not explicitly contrast with the sibling 'hires_patch_message', so it's not a perfect 5.
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?
The description gives no guidance on when to use this tool versus alternatives like hires_patch_message or hires_send_candidate_message. It only mentions that all required fields must be provided, which is a constraint, not a usage context. No alternatives or exclusions are mentioned.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.