Search mail

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

With no annotations provided, the description carries the full burden and excels. It reveals that filters are hard constraints, that search mode depends on body index availability (text vs subjects only), that results include searchable fraction, that threads are grouped with match counts, and that message text is untrusted. This is a comprehensive disclosure of non-obvious behaviors.

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?

Though lengthy, every sentence conveys a distinct, essential fact. The structure is logical: core purpose, then 'IMPORTANT' mode caveat, then grouping behavior, then data safety note. No redundancy or filler; the length is justified by the tool's complexity.

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 the absence of an output schema, the description thoroughly explains what results contain (mode indicator, searchable fraction, thread grouping, match counts, flat list preservation). It also covers limitations (subject-only search) and security context (untrusted markers), making it complete for an agent to invoke and interpret results 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?

The input schema already covers all seven parameters with clear descriptions, so the baseline is 3. The description adds value by stating that filters are hard constraints rather than ranking hints, and by explaining how the query interacts with the body index—semantics not present in the schema. This elevates it above baseline but does not fully detail every parameter's interplay.

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 starts with 'Search messages by free text and/or structured filters', clearly stating the verb and resource. It enumerates specific filter types (sender, mailbox, date range, unread) and notes that filters are hard constraints, which distinguishes it from retrieval tools like get_emails and get_thread. The behavioral detail about conversation grouping further separates it from a flat list tool.

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?

It gives clear context for when to use the tool (searching with filters) and provides an explicit alternative: 'use get_thread on any group worth reading in full'. However, it does not explicitly contrast with get_emails or get_email for scenarios like retrieving a single known message, so it stops short of full when/when-not guidance.

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