read_threadReturn the thread metadata + all messages in chronological order. Use list_inbox first to get a threadId.
| Name | Required | Description | Default |
|---|---|---|---|
| threadId | Yes | thread id from list_inbox |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
Input schema / properties / threadId / descriptionAdded value: +"thread id from list_inbox"Output schema / (root)Previous value: -nullNew value: +{
+ "$schema": "http://json-schema.org/draft-07/schema#",
+ "additionalProperties": false,
+ "properties": {
+ "result": {}
+ },
+ "required": [
+ "result"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotation readOnlyHint=true already signals safe read. Description adds that it returns metadata and messages in chronological order, which aligns with read-only behavior. No contradictions; missing details like pagination or rate limits, but acceptable given annotations.
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?
Two concise sentences: first states what the tool returns, second provides usage guidance. No extraneous words; every sentence is purposeful.
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?
Despite having an output schema (not shown), description covers the key return items (metadata and messages in order). With a single required parameter and clear prerequisite, this is fully sufficient for an agent to use the tool 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 coverage is 100% with threadId description 'thread id from list_inbox'. Description repeats this same phrase, adding no new semantic value. Baseline 3 is appropriate since schema already documents the parameter well.
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?
Description clearly states 'Return the thread metadata + all messages in chronological order', which is a specific verb+resource. It distinguishes from siblings like list_inbox (which retrieves thread IDs) and other thread actions (archive, mark_read, etc.).
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?
Explicitly advises to 'Use list_inbox first to get a threadId', providing clear prerequisite context. Does not include when-not-to-use or alternatives, but for a read tool with a single input, this is sufficient.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.