subscribe_ical

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

Annotations indicate a mutation (readOnlyHint=false) and non-destructive. The description adds context that the calendar must be agent-owned and that org-level calendars won't work. However, it does not disclose behavior on duplicate URLs, error handling, or whether existing subscriptions are overwritten. Adequate but not rich.

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 two sentences: the first states purpose and benefit, the second provides a critical constraint. No unnecessary words; it is front-loaded and efficient.

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 complexity of 4 parameters and no output schema, the description covers purpose and prerequisite but does not indicate what the tool returns on success or what error scenarios exist. Adequate but could be more complete, especially since there is no output schema.

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 parameters are already described. The description reinforces the role of agent_id and calendar_id but adds no new details about url or label beyond the schema. Baseline score of 3 is appropriate.

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 links an external iCal feed to an agent's calendar for availability calculations. The verb 'link' and resource 'iCal feed to agent calendar' are specific, and it is distinct from sibling tools like delete_ical_subscription or sync_ical_subscription.

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 description includes when to use (to include external events in availability) and a critical prerequisite: the target calendar must be owned by the agent. It warns against using org-level calendars, providing clear guidance. It does not explicitly name sibling alternatives but the context is sufficient.

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