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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds real behavioral context: bank holidays and court closures are accounted for, the DCP regime is handled, and the set of computed milestones is enumerated, which tells the agent what the calculation actually produces.

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 compact sentences: purpose first, scope extensions second, input guidance last, with zero filler. The middle sentence is a dense list, but every clause (holidays, closures, DCP) earns its place.

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 14-parameter, high-complexity legal calculator with no output schema, the description conveys jurisdiction, routes, inputs, and the kinds of dates returned. It could go one step further on the returned structure, but with 100% schema coverage and clear scope it is largely sufficient.

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 100%, so the schema already documents all 14 parameters well, including enums and defaults. The description adds only a light natural-language summary of the driving inputs (issue date, service method/time), which is a marginal gain over the schema. Baseline 3 applies.

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+resource ('works out when a claim form and particulars of claim are deemed served in England and Wales') and enumerates the downstream dates produced (acknowledgment of service, defence, extensions, earliest default judgment). This clearly separates it from siblings like calculate_cpr_deadline or calculate_civil_court_fees.

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 scopes jurisdiction (England and Wales), names the two procedural routes (Part 6 vs Damages Claims Portal PD 51ZB), and tells the agent which inputs to supply ('give the issue date, how and when the claim form was served...'). It stops short of naming when to use this tool over a sibling calculator or when it is inapplicable.

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