List messages

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

The description repeats the read-only safety profile already declared by annotations and adds useful behavioral details: newest-first ordering and limit/offset paging. With annotations covering readOnlyHint and openWorldHint, the bar is lower, but it still lacks details on rate limits, result pagination behavior, or what the response fields look like.

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 a single front-loaded sentence that efficiently states purpose, ordering, filter surface, paging, and safety. Every clause earns its place with no redundant or vague phrasing.

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 read-only list tool with no output schema and 10 largely undocumented parameters, the description provides enough to call it correctly: what is listed, ordering, paging, and the full filter surface. It could go further by explaining default page size or response shape, but it is substantially complete.

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 only 40%, so the description must compensate. It names every filter parameter (status, channel, direction in/out, to, from, tag, date range) and clarifies direction semantics and paging, adding meaning beyond the schema for several undocumented parameters.

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 states a clear verb and resource ('List SMS, MMS and RCS messages'), the scope ('on this account'), and the ordering ('newest first'). It distinguishes itself from single-message tools like get_message, but does not explicitly name sibling alternatives such as get_conversation_messages or list_conversations for more specific use cases.

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?

Usage is implied by the filter list and paging description, but there is no explicit guidance on when to use this tool versus related tools like get_conversation_messages for a single thread or list_conversations for conversation-level views. The description does not state exclusions or prerequisites.

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