update_event

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

Annotations already declare idempotentHint=true and destructiveHint=false, covering the safety profile. The description adds 'existing' (won't create) but does not disclose return behavior, partial update semantics, or auth needs beyond what schema/annotations imply.

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 description is well-structured and front-loaded with purpose and usage guidance. However, the Args section is redundant given the schema's comprehensive parameter descriptions, though it is not excessively long and remains readable.

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?

Given the tool's moderate complexity (5 params, 1 required), rich schema descriptions, complete annotations, and an output schema, the description adequately covers purpose, usage, and exclusions. It does not explain return values, but that is handled by the output schema. Minor gap: no mention of handling non-existent event IDs.

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% and each parameter already has a description. The tool description's Args section essentially restates the schema with slight wording differences (e.g., 'workout description or details' vs 'workout prescription steps or notes'), adding no significant semantic value beyond the schema.

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 the tool 'Update an existing calendar event or planned workout' with specific fields (workout targets, start dates, titles). It explicitly distinguishes from create_event, fulfilling sibling differentiation.

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?

Provides explicit guidance: 'Use when modifying workout targets, start dates, or titles' and names the alternative 'To schedule a new event, use create_event.' This gives clear when-to-use and when-not-to-use direction.

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