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

The description discloses the partial-update behavior (unspecified fields stay unchanged), which is a meaningful behavioral trait not directly captured by the annotations (readOnlyHint=false, idempotentHint=true, destructiveHint=false). This adds useful context beyond the structured metadata, though it doesn't discuss error handling or prerequisites.

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?

The entire description is a single, compact sentence with two clear clauses. It is front-loaded with the main action and immediately provides the key usage rule. Every word earns its place; there is no redundancy or 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?

Despite having 17 parameters, the schema descriptions fully cover each property, and an output schema exists to explain return values. The description conveys the core purpose and partial-update behavior, which is sufficient for correct invocation. It lacks explicit guidance on differentiating it from closely related service tools (e.g., update_service_schedule, assign_staff_to_service), but the resource term 'booking service' is reasonably specific.

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?

With 100% schema description coverage, the baseline is 3. The description adds valuable meta-semantics by explaining that parameters are treated as 'fields to change' and can be passed selectively, which clarifies how to use the optional properties beyond what the schema alone states.

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 clearly states what the tool does with a specific verb and resource: 'Update an existing booking service.' The word 'existing' distinguishes it from creation tools, and the term 'booking service' helps differentiate it from other service-related tools like update_service_schedule or update_service_package.

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 instruction to 'Pass only the fields you want to change' provides clear guidance on partial update semantics, indicating that omitted fields will remain unchanged. It does not explicitly mention alternatives or exclusions, but it gives coherent context for when to use this tool (updating an existing service's fields).

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