search_messages

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

With no annotations, the description carries the full burden. It does disclose two useful traits: the operation is read-only and message bodies are excluded from matching. However, it says nothing about permissions, result ordering, pagination, or what 'recent' means relative to the scan_limit parameter.

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?

Two short sentences, zero filler, with the core action front-loaded and the read-only/no-body-search caveat immediately after. Every clause earns its place.

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?

For a five-parameter read tool with no output schema and no annotations, the description covers purpose, safety profile, and search scope. The one gap is the vague 'recent' framing, which leaves the interplay between default result limit and scan_limit unstated.

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 all five parameters are documented in the schema itself; baseline is 3. The description's 'by subject or sender' loosely restates the query parameter's documented semantics and adds no syntax or format guidance beyond it.

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?

States a specific verb (search) plus resource (messages) and narrows the match field to subject or sender within one mailbox. That is enough to separate it from list_messages (unfiltered listing) and get_message (single retrieval), though no sibling is named explicitly.

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 phrase 'search recent messages by subject or sender' implies the use case, and 'bodies are not searched' implies a boundary, but no alternative tool is named and no explicit when/when-not condition is given. Usage must be inferred from the sibling set.

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