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

Beyond annotations (readOnlyHint=false, destructiveHint=false, idempotentHint=false), it discloses the required `calendar:write` scope, that the first call is non-mutating, that unknown fields are refused by name, and what the first call returns. It does not say whether an existing feed is replaced or rejected, which matters given idempotentHint=false.

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 auth requirement, then the two-phase protocol. Sentences are dense and purposeful, though the parenthetical about field refusal is slightly convoluted and the ordering of 'Two calls' before explaining what the first call does costs a little clarity.

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?

For a low-parameter mutation tool with no output schema, the definition covers auth, the confirmation protocol, first-call return values, and validation behavior. The main gap is what the second call yields (the link itself?) and what happens to any pre-existing feed.

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 the schema already documents confirm_token, but the description adds workflow meaning: omit it on the first call, and on the second pass the same arguments plus the token the first call answered. That clarifies sequencing the schema cannot express.

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 first sentence states a specific verb and resource: creating a calendar subscription link (feed). Combined with the two-call explanation, an agent knows exactly what the outcome is. It does not explicitly distinguish itself from siblings such as rotate_calendar_feed or get_calendar_feed, so it falls short of 5.

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 spelled out for the two-step flow: call once, show the summary to the person, then call again with the same arguments plus confirm_token only after agreement. There is no guidance on alternatives (e.g. rotate_calendar_feed when a link already exists) or what to do if a feed is already present, so it is clear but incomplete.

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