gcal_update_event

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

Annotations already establish readOnly=false, idempotent=true, and destructive=false. The description adds the critical nuance 'Only provided fields are changed; omitted fields remain as-is,' which prevents an agent from assuming unlisted fields get cleared, and it discloses the return contract ('JSON dict of the updated event'). This is consistent with all three annotation hints, so no contradiction.

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 purpose sentence comes first, followed by the single most important behavioral note about partial updates, then a compact args list and a one-line return statement. Every line earns its place with zero 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?

Given the rich per-property schema, annotations, and output schema, the description covers the essentials: what it does, partial-update semantics, required event_id, parameter roles, and return format. It omits edge-case behavior such as error handling for an invalid event_id or permission requirements, which prevents a 5 but leaves nothing critical missing for a correct first call.

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?

Despite the 0% coverage signal, the schema itself documents each property (e.g., 'New start datetime (ISO string)', 'New title (leave blank to keep existing)'). The description lists every parameter and groups title/start/end/description/location as 'Fields to update,' adding a bit of role clarity, but it provides no format or constraint details beyond what the schema already 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?

Opens with a specific verb and resource: 'Update one or more fields on an existing Google Calendar event.' The 'existing' qualifier and 'one or more fields' scope distinguish it from gcal_create_event, gcal_delete_event, and gcal_get_events without needing to inspect sibling schemas.

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?

Usage is implied rather than stated: 'existing' plus the required event_id signal that this is for modifying an already-created event, not for creating one. However, no alternatives are named and no explicit when-not-to-use conditions are given, so the agent must infer the selection logic from sibling names.

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