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

The annotations already declare write, destructive, idempotent and open-world hints, so the description only needs to add context – which it does, by spelling out PATCH-style merge behavior and the cafe/hot bar restriction on actual_covers. It does not cover what an overwrite destroys (e.g. prior forecast values being replaced) or any auth requirements, leaving some room above the annotation floor.

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?

Four short sentences, front-loaded with the WRITE marker and the core action, then the constraint, the idempotency note and the endpoint. Nothing is padded and each sentence adds a distinct fact.

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 partial-update call with no output schema, the description covers the essential risks: applicability restriction, merge semantics and idempotency. The remaining gap is the response shape after the PATCH and whether prior values are recoverable.

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%, so all three parameters are already documented, including the cafe/hot-bar constraint on actual_covers. The description's parameter-related content largely restates that schema text; the one genuine addition is confirming that omitted optional fields are left untouched, which is only a marginal gain.

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 ('set the forecast and/or actual number of covers on an event') with an explicit WRITE marker and the underlying endpoint (PATCH /events/{id}). This clearly distinguishes it from siblings like parsley_record_event_sales or parsley_create_event, which also touch events.

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?

Gives clear operating conditions: partial-update semantics ('Only the fields you pass change'), a hard applicability rule ('actual_covers works only on cafe/hot bar events'), and idempotency ('Setting the same values again has no further effect'). It stops short of naming alternatives or when-not-to-use cases, e.g. whether forecast covers should be set here versus at creation time.

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