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

Annotations already cover safety (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the description's job is to add operational detail, and it does: the no-id path returns exactly the 10 most recent broadcasts, which is a real result-set bound rather than a restatement. It still leaves the metric definitions, time window, and response shape undisclosed.

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 sentence that front-loads the resource and payload, then folds the branching condition into a trailing clause. Nothing is redundant and nothing needs reordering.

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 one-optional-parameter read tool with full annotation coverage, the description covers both modes and the result-set cap, which is what an agent needs to call it correctly. The remaining gap is that an agent cannot predict which engagement metrics come back, though with no output schema that is a minor omission for a stats reader.

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 bare 'broadcast_id' field carries no meaning on its own; the description partially compensates by establishing that the id identifies a single broadcast and that omitting it switches to the recent-list mode. It does not state the id format or confirm the field is optional for the listing behavior.

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 names a specific resource and operation set: delivery and engagement stats for a broadcast, readable either as a single-broadcast lookup by id or as a listing of recent broadcasts. No sibling tool in the provided list touches broadcasts, so an agent can route to it unambiguously. It stops short of 5 because 'stats' remains an undefined bundle of metrics.

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 two invocation modes are stated explicitly: supply an id for one broadcast, omit it to get the 10 most recent. That is clear operative context an agent can act on directly. It does not name alternatives or exclusions (e.g., how to get a broader historical range), which keeps it from a 5.

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