days_until

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

With no annotations, the description carries the burden of behavioral disclosure. It supplies meaningful context: the Sydney calendar/timezone conversion for `now`, and that `now` may be an ISO datetime with offset or a date. It does not claim destructive/read-only behavior, so there is no contradiction, but it stops short of describing edge cases like invalid ids or day-count inclusivity.

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 concise and front-loaded: the main purpose appears in the first sentence, followed by the `now` parameter detail using backticks, and a one-sentence legal/informational disclaimer. The disclaimer is slightly peripheral to tool invocation but not bloated.

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 two-parameter tool with an output schema, the description covers the required target values, the optional `now` behavior, and the timezone semantics needed to invoke it correctly. It is complete enough without needing to describe return values because an output schema is present.

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 description coverage is 0%, so the description must compensate for the bare schema. It does so thoroughly: it lists the valid deadline id values, allows YYYY-MM-DD as an alternative target format, and explains the accepted formats and Sydney conversion for `now`. This adds substantial meaning beyond the parameter names.

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 that the tool computes days from today on the Australia/Sydney calendar to either a named deadline id or an explicit date. It distinguishes itself from sibling rule-list/retrieval tools by being a date-calculation tool, and it enumerates the accepted deadline ids.

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: the agent can infer the tool is for calculating days until a known deadline or date. However, the description gives no explicit guidance on when to prefer this over sibling tools such as list_rules, get_rule, or search_rules, and it does not mention exclusions or alternatives.

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