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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description adds real behavior: the exact .ics contents, alert timing at 9am the day before and on the day, and crucially 'Nothing is stored.' That persistence disclosure is the kind of context annotations cannot convey.

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 one-line purpose, then efficient detail on the artifact and routing. Sentences are long and dense (the .ics contents run on), but every clause carries actionable information and nothing is padded.

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 output schema, the description must describe the return value, and it does so concretely (calendar file contents, event timing, alerts). Combined with the 'nothing is stored' guarantee and the get_bill_script routing note, an agent has what it needs to call this correctly.

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 bill/provider/country/deal_ends are already documented with their own descriptions, and the tool defers to get_bill_script for their meaning. The description adds only the deal_ends positioning, so baseline 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?

States a specific verb and artifact ('Returns a calendar file (.ics) with an all-day event') rather than restating the title. It names the exact event timing and payload (30 days before deal end, full script, offers, confirm-in-writing), so an agent can distinguish it from get_bill_script and get_bill_help without opening a schema.

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?

It ties itself to the routing flow, noting 'get_bill_script gives this link as add_to_calendar when deal_ends is given,' which tells the agent when this tool is the right target. It stops short of explicit when-not guidance or naming alternatives directly, so it's clear context rather than full routing rules.

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