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

No annotations are provided, so the description carries the full burden and discloses nothing beyond the operation name. It does not say what 'active' filters on, whether membership vs. recent activity is returned, whether admin rights are required, or how results are bounded or ordered.

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?

It is a single short line with zero waste and the prefix is front-loaded, but the brevity is under-specification rather than economy — the fragment leaves key distinctions unstated rather than compressing them.

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 tool with no annotations, no output schema, and a near-duplicate sibling, the description should at minimum explain the relationship to list_group_participants and what the listing represents. It omits both, so an agent would have to guess or fall back on schema inspection.

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%, with defaults and the origin of chat_id ('from list_dialogs') documented inline, so the schema already does the heavy lifting. The description adds no additional meaning about how limit, active_days, or chat_id interact, so baseline 3 applies.

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 fragment names a verb and resource ('list active chat participants') and scopes it to Telegram, so the basic operation is inferable. However it gives no hint of how it differs from the sibling 'list_group_participants', which on its face sounds like the same operation, leaving an agent unable to discriminate between the two.

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 statement of when to use this tool rather than list_group_participants or list_dialogs, and no prerequisites such as needing a chat_id obtained from list_dialogs. Usage is only implied by the name.

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