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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds valuable behavioral context: it specifies the data source (OpenAccountants tax calendar) and that the response marks jurisdiction_source, which helps the agent interpret results. It doesn't describe output format, but the presence of an output schema mitigates that gap.

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 moderately long but every sentence adds value: it states purpose, usage triggers, and a nuanced parameter behavior. It is front-loaded with the primary purpose and avoids redundancy. Slightly longer than strictly necessary, but no waste.

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 an output schema, the description covers all essential aspects: what it returns, when to use it, and how to handle optional parameters. The agent has everything needed to invoke it correctly without additional inference. No significant gaps remain.

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 input schema already describes both parameters with details like default and max for horizon_days, and acceptable formats for jurisdiction. The description enhances this by clarifying the optional jurisdiction behavior for signed-in users, which is not fully captured in the schema. This adds value beyond the schema, justifying a 4 over the baseline 3.

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 states a specific verb ('get') and resource ('deadlines') and clearly defines the scope: 'Upcoming filing/payment deadlines and recurring filing rhythms ... for a country or US state.' This unambiguously separates it from siblings like search_rules or list_jurisdictions, which serve different purposes.

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 gives explicit triggers: 'Use it whenever the user asks "when is X due", mentions a filing date, or when a heads-up about an imminent deadline would help.' It also explains the optional jurisdiction behavior for signed-in users, leaving no ambiguity about when to call and how to handle the optional parameter.

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