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

No annotations are provided, and the description 'Get Slack direct messages.' discloses no behavioral traits. It does not state return format, pagination, authentication requirements, or whether it returns sent vs. received DMs. The description relies entirely on the tool name for behavior, which is insufficient.

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, clear sentence with no unnecessary words. It communicates the core purpose efficiently and is appropriately sized for the tool's simplicity.

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?

Although the tool is simple with no parameters and no output schema, the description does not explain what output to expect (e.g., list of messages, metadata, format). It also omits any details about the scope (e.g., all DMs or only unread). This incompleteness could lead to incorrect assumptions about the return data.

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?

The tool has zero parameters, and the schema shows an empty object. The baseline for zero parameters is 4, as there are no parameter semantics to explain. The description does not need to add parameter details, and none are missing.

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 clearly states the tool's action ('Get') and resource ('Slack direct messages'), using a specific verb and noun. It distinguishes itself from sibling tools like 'get_slack' (broader) and 'get_teams_dms' (different platform), making its purpose unambiguous.

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?

There is no guidance on when to use this tool versus alternatives such as 'get_slack' or 'search_slack'. The description does not mention exclusions, prerequisites, or preferred contexts. For a tool with zero parameters, users would benefit from context like whether it returns only recent DMs or the user's own DMs.

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