List messages

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

Beyond the readOnly/idempotent annotations, the description discloses meaningful behavior: messages from blocked members/spaces are included, show_deleted includes tombstones, and the tool works only with user authentication. This adds context about what the tool returns and its access constraints, well beyond what annotations alone convey.

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 compact and information-dense, with no filler. Core purpose is front-loaded, followed by filters, ordering, deletion behavior, polling guidance, and authentication requirements, with each sentence contributing distinct and useful information.

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 7 parameters and no output schema, the description compensates well by listing the returned fields, filter semantics, pagination strategy, deletion behavior, and auth constraints. An agent has enough context to decide when to call this tool and to construct a correct request.

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 the schema already documents each parameter. The description adds value by explaining output fields, the default ordering, the meaning of created_after for incremental polling, and that text filtering must happen client-side, though a minor ambiguity remains around calling only created_after and thread_name 'filters' when show_deleted also filters.

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 opens with a specific verb and resource: 'Lists messages in a space', and further clarifies scope by including messages from blocked members and spaces and enumerating returned fields. This clearly distinguishes the tool from siblings like get_message (single message), list_spaces, and send_message.

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 description provides clear operational guidance: there is no text search, clients must match client-side, and users should poll incrementally with created_after + page_token. It also states authentication requirements and scope prerequisites, though it does not explicitly name alternative tools for text search or single-message retrieval.

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