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

With no annotations provided, the description carries the full burden of disclosing behavior. It does add a key behavioral note: 'Holiday data is United States federal only and every response says so,' which informs the agent about a limitation. However, it does not mention any side effects, permissions, or edge cases (e.g., timezone handling details), though these are partially covered by schema parameter descriptions. The description is not contradictory but is sparse on operational behavior.

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 exceptionally concise: a single sentence stating purpose and listing ops, followed by a critical note about US federal holiday data. Every word earns its place, and the purpose is front-loaded. There is no fluff or repetition of schema details.

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?

Given the tool has 7 parameters and 4 operations but no output schema, the description could be more complete. It does not explain the output format or provide usage examples, though the schema covers parameter specifics. The description adequately orients the agent but leaves operational nuances (e.g., which op requires which fields) to the schema. For a tool of moderate complexity, this is acceptable but not comprehensive.

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 86%, so the baseline is 3. The description lists the operations but does not add meaning beyond the schema's enum for 'op' or the per-parameter descriptions. The description's mention of 'ops' is redundant with the schema, and it does not clarify relationships between parameters (e.g., which params are needed for each op). Thus, it provides minimal additional parameter semantics.

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 the tool's purpose: 'Date arithmetic against a real calendar' and explicitly enumerates the four operations (add_business_days, diff, tz_convert, is_us_federal_holiday). This distinguishes it from sibling tools like 'clock' (time) and 'calc' (generic arithmetic) without ambiguity.

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 implies usage through the operation names (e.g., 'add_business_days' suggests when to use it for business day calculations), but it does not explicitly contrast with alternatives or state when not to use this tool. There is no mention of when 'clock' or 'calc' would be more appropriate, leaving the agent to infer from context.

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