calendar_feed_update

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

With no annotations, the description carries the full burden and does well: it discloses the mutation nature, the specific failure mode (NOT_ENABLED), the two distinct return shapes for enabled/disabled states, and a security warning that the link is a credential readable by anyone holding it. It omits auth requirements and whether omitted fields retain their current values.

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?

Front-loaded with the action, then the failure condition, then the return contract and the security caveat. Although the return-value inventory is long, there is no output schema, so every field listed earns its place.

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?

With no annotations and no output schema, the description compensates by enumerating the exact response fields for both enabled and disabled states and flagging the credential risk. Only permissions/auth expectations and partial-update semantics are left unstated.

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?

Two parameters at 100% schema description coverage, so the schema already documents includeExpiries and includeFiscal. The description only echoes those names in the return shape and adds no semantics (defaults, partial-update behavior) beyond the schema, which is the baseline-3 case.

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+resource: 'Change what the calendar subscription contains.' That is a distinct action from calendar_feed_get/enable/disable, so an agent can select it without opening the schema, but the description never names or contrasts those siblings.

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?

'Fails with NOT_ENABLED when it is off' gives a clear precondition that implies the agent must call calendar_feed_enable first, which is strong context. It stops short of an explicit when-to-use/when-not statement or naming the alternative tools.

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