search_indexed_emails

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds context by stating it makes no IMAP connection and relies on a local index, which implies potential staleness. It also introduces inline field shortcuts, but does not detail behavior when the index is empty or result ordering, though this is a minor gap given the annotation coverage.

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 concise (about four sentences), front-loaded with the core purpose, and each sentence adds essential guidance. It avoids redundancy with schema and annotations, making every line valuable.

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 17 parameters and no output schema, the description does a good job explaining the tool's niche (offline index search versus live IMAP) and usage conditions. It does not describe return format or pagination beyond the limit parameter, but the schema covers parameters, and the key contextual distinction from siblings is thoroughly addressed.

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 100%, so baseline is 3. The description adds value by explaining field shortcut syntax directly (from:alice@example.com, to:bob, subject:invoice, label:Archive, domain:acme.com), which enriches understanding of how the query parameter can be used alongside structured filters, beyond what schema parameter descriptions individually provide.

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 the tool's function: 'Search the local SQLite mailbox index without making any IMAP connection.' It specifies the resource (local SQLite index) and distinguishes from sibling search_emails by highlighting offline capability versus live IMAP.

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?

Explicit usage guidance is provided: 'Prefer search_emails when you need live IMAP results or when the index is stale or empty. Prefer this over search_emails when the index is current. Use search_emails if messages were received after the last sync.' This clearly communicates when to use this tool versus the alternative.

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