List chats

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

With no annotations, the description carries the full burden and does reasonably well: it discloses the local-database source, the SCOPE failure condition tied to MESSAGES_SCOPE / MESSAGES_ALLOW_UNSCOPED, the returned fields, and an explicit exclusion ('Does not return attachment bytes'). It stops short of permissions or pagination behavior beyond the 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?

Purpose is front-loaded and the return-value sentence earns its place, but the SCOPE sentence ('No MESSAGES_SCOPE and MESSAGES_ALLOW_UNSCOPED is unset') is grammatically broken and ambiguous, and the enumeration of sibling tools adds noise rather than routing guidance.

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 and no annotations, the description compensates by naming the returned fields and the SCOPE error condition, which is enough for an agent to call it and interpret results. Minor gaps remain around ordering of 'recent' conversations and the absence of explicit sibling routing.

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% (limit and query both documented in-schema), so the baseline is 3. The description adds no additional meaning for either parameter, for example what counts as a match for 'query'.

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 and resource ('List recent conversations') and scopes it precisely to the local Messages database covering iMessage and SMS. It alludes to sibling tools ('list/search/thread/send/watch') but does not name them directly, so differentiation from messages_search and messages_get_thread requires inference.

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?

Offers one concrete usage tip ('Prefer guid to remember a thread across launches') but never says when to choose this tool over messages_search or messages_get_thread. Usage is implied by the 'recent conversations' framing rather than stated as an explicit rule.

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