overview

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

No annotations are provided, so the description carries the burden of behavioral disclosure. It somewhat handles this by specifying the grouping logic ('newest first', 'per conversation') and the output fields. However, it doesn't describe the account parameter behavior, vague 'days' semantics, or any rate/limit considerations. It's a read operation implied by 'activity' but not explicitly stated.

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?

Extremely concise — two short sections. The first sentence states the purpose, the second outlines output fields, and the third provides usage guidance. Every sentence earns its place with zero filler.

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?

An output schema exists which handles return value explanation, and the description covers the grouping logic, ordering, and its place in the API workflow. Missing parameter semantics is the main gap, but for an overview/aggregation tool with just two params (one optional with defaults), the description is reasonably complete. Sibling differentiation is a minor gap given recent_messages and list_conversations overlap.

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 0%, and the description provides zero parameter documentation. The 'days' parameter implies a time window but its defaults/format aren't mentioned, and 'account' with null default is completely unexplained. With 2 parameters and no schema descriptions, the tool description should compensate but does not.

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 uses a specific framing ('Who messaged you: recent activity grouped by conversation') with clear output structure (title, message count, distinct senders, last message + time). It clearly states the resource (recent activity) and the grouping (by conversation, newest first). It doesn't explicitly differentiate from siblings like recent_messages or list_conversations, though the grouping by conversation with sender stats is fairly distinct.

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 explicitly states this is a 'Great first call to get the lay of the land before drilling in', providing clear guidance on when to use it (as an entry point before deeper tools). It doesn't mention specific alternatives or when NOT to use it, but the suggested workflow context is actionable.

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