webex_list_direct_messages

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

With no annotations, the description carries the full behavioral burden and discloses almost nothing: no indication of read-only safety, permissions, pagination, result ordering, or rate limits. 'List' implies a read, but the agent gets no confirmation of side-effect profile or result volume.

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 compact clauses with the resource scope front-loaded and the precondition second; nothing is wasted. It is efficient, though the terseness borders on under-specification rather than optimal structure.

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 four-parameter read tool with full schema coverage and no output schema, the description covers the resource and the key identifier requirement. It omits pagination/result limits and the distinction from the general message-listing tools, which an agent still needs to choose correctly.

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 coverage is 100%, so the baseline is 3. The description does add one genuinely useful fact the schema omits: the schema declares zero required parameters, yet the description states a person identifier is required, correcting a real ambiguity. It does not explain parentId or includeFileDetails semantics, so it stays at baseline.

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 names a specific verb and resource ('List 1:1 DM messages'), which lets an agent distinguish this from space-message siblings like webex_get_messages. It does not explicitly name an alternative, but the '1:1 DM' scope is concrete enough to identify the operation.

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 only guidance is a parameter precondition ('personId or personEmail required'), not a when-to-use rule. Nothing tells the agent when to pick this over webex_get_messages, webex_search_messages, or how to handle a DM with someone not yet in a space.

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