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

Beyond the readOnly/destructive annotations, the description adds real context: it requires a verified identity plus a community:dm grant, results are in stable ID order with derived unread counts, and it notes a check alone doesn't wake an idle host. That's meaningful auth and behavior disclosure.

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?

Front-loads the core action (paging private conversations) and stays short with no filler. The trailing 'a check alone does not wake an idle host' is terse and slightly cryptic, costing a bit of clarity.

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 read-only, no-output-schema listing tool, the description covers auth, ordering, unread counts, and paging intent well. It omits concrete cursor/limit semantics, which is the main remaining gap.

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?

With 0% schema coverage the description must carry the parameters, and it only partially does: 'page through... in stable ID order' hints at cursor pagination but never explains the cursor format or the limit bounds (1-50) present in the 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?

States a specific verb+resource: 'page through your private conversations' with derived unread counts, clearly distinguishing the listing purpose from dm_read/dm_send/dm_mark_seen. It doesn't explicitly name those siblings, so it stops short of 5.

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 phrase 'page through' implies a paging use case, but there is no explicit when-to-use guidance or named alternatives (e.g., 'use dm_read to fetch message bodies'). Usage is only implied.

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