Search mail

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond that: it enumerates the returned fields (id, thread id, date, from, to, subject, snippet) and defines the empty-query fallback, which shapes what the agent should expect back. It does not mention pagination or result limits, though max_results and page_token are documented in the schema.

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?

Three short sentences, each doing distinct work: scope and syntax, then return fields and the read_email handoff, then the empty-query default. Front-loaded with the search scope, and nothing is padding.

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 no output schema, the description correctly spells out the returned fields and routing to read_email for bodies. For a read-only search tool whose annotations carry the safety profile, this is close to complete; only pagination and the 100-result cap are left to the schema, which is a minor gap.

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%, so the parameter docs already carry the syntax detail, making 3 the baseline. The description nonetheless adds meaning the schema lacks: it explains the empty-query default behavior and reinforces account="all" as an aggregation mode, which affects how the agent interprets the results.

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 uses a specific verb and resource ('Search one mailbox, or all of them... using Gmail search syntax') and names its scope precisely. It goes further than the sibling names alone: it hands off 'full body' retrieval to read_email, so an agent can tell search_emails apart from read_email and read_thread without opening either schema.

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 operating context: the account="all" mode for cross-mailbox search, the read_email alternative for full bodies, and the default that an empty query returns the newest mail. It does not address when to prefer this over the generic 'search' sibling, which is the one routing question an agent still has to infer.

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