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

The readOnlyHint=true and openWorldHint=true annotations already establish the safety profile, and the description is consistent with a read operation. It adds a performance-oriented note about narrowing results to keep the response small, but says nothing about pagination, permissions, or response shape.

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 two short sentences with no wasted text. The core purpose is front-loaded, followed immediately by the filtering tip.

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 three-parameter list tool with no output schema and 0% schema description coverage, the description leaves important gaps. It omits profileId and does not explain how accountId relates to profileId or what the returned message history contains.

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 the description carries the full burden of parameter semantics. It mentions platform and accountId as filters but omits profileId entirely and does not clarify the distinction between accountId and profileId. It also does not explain the platform enum's broader set of values beyond Instagram and Facebook.

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 specific verb and resource: reading direct message history. It distinguishes the tool from send_message and list_comments/list_posts by focusing on DM history. However, it names only Instagram and Facebook while the platform enum includes many other networks, so the stated scope is narrower than the schema suggests.

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 gives one useful usage hint: filter by platform or accountId to keep the response small. It does not explicitly say when to use this tool versus list_comments, list_posts, or send_message, nor does it mention exclusions or prerequisites.

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