Send a substantive reply in an existing thread, preserving originator and routing.
Send a substantive reply in an existing thread, preserving originator and routing.
| Name | Required | Description | Default |
|---|---|---|---|
| cc | No | ||
| to | No | ||
| body | Yes | ||
| subject | No | ||
| priority | No | normal | |
| message_id | Yes | ||
| references | No | ||
| attachments | No |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v1.4.0Input schema / properties / priorityAdded value: +{
+ "default": "normal",
+ "title": "Priority",
+ "type": "string"
+}v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral burden. It discloses a meaningful trait—preserving originator and routing—and clarifies that the reply is attached to an existing thread. Still, it does not mention side effects, required permissions, or failure modes, so coverage is partial.
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, front-loaded sentence with no filler. It earns its place by stating the action and a key behavioral constraint, though 'substantive' is somewhat extraneous and could be removed without losing information.
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 an 8-parameter action with no annotations and no parameter explanations, this description is too thin. It leaves questions about reply routing behavior, relationship to iam_send, and how message_id/references work. The presence of an output schema reduces return-value ambiguity but not these usage gaps.
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 0% and the description mentions none of the 8 parameters. The agent receives no help beyond parameter names like message_id, references, or priority, and the description does not compensate for the missing schema detail.
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 names a clear action and object: 'send a substantive reply' in 'an existing thread'. The phrase 'preserving originator and routing' adds meaningful distinction from a generic message send, though 'substantive' is vague and not explained.
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 implies the tool should be used when replying within an existing thread, which gives some context. However, it does not explicitly state when not to use it or mention alternatives like iam_send for new messages, leaving the routing decision partially inferred.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.