list_messages

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

With no annotations, the description must carry behavioral disclosure. It does add ordering ('newest first'), page_token-based pagination, and the ability to filter, but it leaves 'recent' undefined and never states what the response contains or whether there are permission/rate limits.

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 front-loaded with the core action; the Args block is clean, each parameter has a one-line purpose, and the filter example is valuable without bloat.

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 4-parameter read tool with no output schema, the description covers inputs and ordering but omits the return shape (what fields each message has), pagination limits, and any auth or error conditions. The 'recent' qualifier is also vague, so an agent cannot fully predict behavior.

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 0%, so all parameter meaning comes from the description. It explains each parameter: space with a concrete example, page_size semantics, page_token usage, and filter_expr with a query example. This fully compensates for the empty schema.

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?

Description uses a specific verb ('List'), specifies the resource ('messages in a Google Chat space'), and adds ordering detail ('newest first'), making it clearly distinct from siblings like send_message (write), list_spaces (different resource), and search_messages (query-based).

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?

No guidance on when to choose this over search_messages or how it relates to list_spaces. The purpose implies per-space browsing, but alternatives are never mentioned, so the agent must infer from the name.

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