search_threads

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

No annotations exist, so the description carries the full burden. It discloses that the tool searches across threads and returns summaries, but does not explicitly state it's read-only or describe pagination behavior beyond limit. The requirement for inbox_id/domain_id is stated but not the logical combination. Adequate but not comprehensive.

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 very concise: three sentences plus a bulleted list. It front-loads the purpose and return format, immediately followed by a key requirement, then parameter details. No filler or redundant 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?

With 4 parameters, no annotations, and an output schema, the description covers the essential aspects but omits details like how multiple filters combine (AND/OR), behavior on no results, or error conditions. It is functional but not fully complete for complex usage.

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%, so the description must compensate. It does so by listing all parameters and adding meaning: query = searches subject and content, limit = max results 1-100 (default 20), inbox_id = filter by inbox (recommended), domain_id = filter by domain. This adds significant value beyond the bare schema.

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 states 'Search across email threads by subject or content' which is a specific verb+resource. It also mentions the return format. While it doesn't explicitly contrast with sibling list_threads, the purpose is 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 provides a usage requirement ('provide at least one of inbox_id or domain_id') but gives no guidance on when to use this tool versus alternatives like list_threads or search_sms. No explicit when-to-use or when-not-to-use guidance.

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