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

Annotations already declare this is a read-only, idempotent, non-destructive, closed-world operation, so the safety profile is covered. The description adds genuinely new behavior: the default window is the last 30 days, the counters break down by who answered (person, rule, AI), and DM response times plus a daily series are produced. It does not say whether the series is zero-filled or how time zones beyond UTC are handled, keeping it short of a 5.

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?

A single dense sentence that front-loads the core action and metrics and closes with the default range. Every clause carries information; there is no filler or repetition of the title.

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, all-optional read tool with no output schema, the description covers what is measured, the default window, and the shape of the result (counts, response times, daily series). It is nearly complete; only the response container/format and platform behavior remain unstated.

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 75%, with 'from' and 'to' well documented and channel_id pointing to list_channels, so the schema carries most of the load. The description adds the meaningful default (last 30 days) that the schema omits, but says nothing about the platform parameter whose enum values are undocumented 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?

The description gives a specific verb-and-resource pair ('count DMs and comments received and answered') and enumerates the metrics returned: response times and a daily series. It clearly distinguishes an analytics/aggregation tool from list-style siblings like list_messages or list_comments, though it never names a sibling explicitly.

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?

Usage is only implied: 'count ... over a date range' signals this is for aggregate reporting rather than raw message retrieval, and the stated default range implies the parameters are optional. There is no explicit when-to-use versus get_usage, get_messages, or list_conversations, and no when-not guidance.

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