search_emails

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

Description reveals that it uses live IMAP filters, performs optional local post-processing, and includes a warning on the includeSnippet parameter about prompt-injection risk. Annotations already mark readOnlyHint=true, so no contradiction. The description adds valuable behavioral details beyond the annotation.

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 sentences: first announces purpose, second gives usage guidance, third offers alternative. Each sentence adds value; no wasted words. Front-loaded with the core action.

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 23 parameters fully described in schema and no output schema, the description covers core behavior, usage guidance, and an important security caveat. It does not describe return structure, but that is partially mitigated by the schema's parameter descriptions and the tool's likely standard email list output.

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 baseline is 3. However, the description adds context that some filters (label, threadId, mailboxRole, etc.) are applied locally after IMAP fetch, and it includes a security warning for includeSnippet. This goes beyond the schema's parameter descriptions.

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 explicitly states 'Search emails via live IMAP filters with optional local post-processing for attachments and labels.' This provides a specific verb ('Search') and resource ('emails') and distinguishes from sibling 'search_indexed_emails' by mentioning the live IMAP method.

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?

'Use when you need real-time results or must find messages received after the last sync. Prefer search_indexed_emails when the local index is current...' Provides clear context for when to use this tool and explicitly names the alternative.

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