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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so 'Nothing is written or sent' largely restates the structured safety profile. The description does add real value by enumerating what the preview returns (source identity, matching steps, mapped contact fields), which is not captured anywhere else since there is no output schema.

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 front-loaded sentence with the key qualifier ('Dry run') first and a compact parenthetical listing the outputs. Every clause earns its place, though the parenthetical could be slightly tighter.

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 2-parameter read-only tool with full schema coverage and clear annotations, the description covers purpose, side-effect safety and the shape of the result. The only mild gap is the absence of guidance on what to do with the preview result or how to follow up.

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 100%, with both parameters documented, including where source_id comes from. The description only loosely restates that the event should look like what the external system sends, adding little beyond the nested-object schema description. 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?

States a specific verb and resource ('Dry run: show what a source would do with a sample event') plus the scope of that preview. An agent can tell it is a non-mutating simulation against an event source. It does not name a sibling it is unlike (e.g. preview_saved_version, list_event_connection_events), so it falls short of a 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?

'Dry run' implies the testing-before-activation context, so the usage is inferable. However, there is no explicit statement of when to call this instead of alternatives such as list_event_connection_events or pause_event_connection, and no stated prerequisites beyond the source_id reference.

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