Read Email Thread

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

The description discloses critical behaviors not covered by annotations: bodies are excluded, messages are ordered newest first, and the meaning of 'has_more' with no offset/cursor is explained. This adds significant transparency beyond readOnlyHint and idempotentHint.

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 four sentences, each conveying essential information without redundancy. It front-loads the core purpose and immediately follows with usage distinctions and caveats, maximizing clarity per word.

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 presence of an output schema, the description need not list return fields. It covers the thread scope, ordering, body exclusion, and pagination limitations, making it fully complete for a read operation with no unsupported scenarios.

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 adds meaning to the 'limit' parameter by explaining that raising it is the only way to see more results since there is no offset/cursor. It also reiterates that item_id can be a conversation_id, though the schema already states this. This compensates for the schema's lack of description on 'limit'.

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 clearly specifies the tool's function: reading an entire email conversation, ordered newest first. It distinguishes itself from sibling tools by explicitly contrasting with search (which only returns matched messages) and get_email (which returns a single message), making the unique purpose unambiguous.

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 explicitly states when to use this tool: 'The only way to read a thread in full' and contrasts it with search and get_email. It also provides follow-up guidance on using get_email for message bodies, giving clear decision-making context.

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