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

Annotations already mark this as read-only, so the description doesn't need to cover safety. It adds meaningful behavioral detail beyond the schema by noting that weekend-observed shifts are included, flagging a common source of errors. This gives the agent useful expectations about the returned data.

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?

Three concise, purposeful sentences. The first states the action and output, the second gives legal context, and the third highlights the non-obvious weekend shifts. No redundant words or filler.

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 simple one-parameter read-only tool with no output schema, the description is complete. It states what is returned (every holiday with observed date), why it matters (court-day counting and deadline roll-off), and a key correctness detail (weekend shifts). An agent can correctly select and invoke this tool with the provided information.

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?

The schema fully documents the single 'year' parameter with a range and description ('Four-digit year'). The tool description adds little beyond restating 'for a given year,' so it does not meaningfully improve on the schema. Baseline 3 applies given 100% schema coverage.

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 uses a specific verb ('List') and a specific resource ('every California judicial holiday for a given year') with a defined scope. It clearly distinguishes this holiday-lookup tool from the sibling deadline calculators, which are about adding days or computing deadlines.

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 explains the practical context: these are the days excluded when counting court days and when deadlines roll off under CCP section 12a. This tells the agent when the tool's output is relevant, though it does not explicitly name an alternative or state when not to use it.

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