update_contract_coverage

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

With no annotations provided, the description carries the full burden and thoroughly discloses behavioral traits: dedupe semantics, validation rejection (not silent ignore) for invalid or non-pair course IDs, and the terminal state rule for completed contracts. It leaves little ambiguity about edge cases and side effects.

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 a single dense paragraph, but every clause earns its place: purpose, validation rules, dedupe behavior, and terminal-state restriction. There is no filler or redundant wording, making it efficient for an agent to parse.

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 mutation tool with no annotations and no output schema, the description covers purpose, constraints, validation, dedupe, and lifecycle restrictions, which is strong. It lacks an explicit description of the return value or success/failure response, but the behavioral specification is otherwise complete.

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 provides 100% parameter descriptions, so the baseline is 3. The description adds meaningful semantics by stating that at least one of add_course_ids or remove_course_ids must be a non-empty array, and explains dedupe/validation behavior beyond what the schema covers.

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 the specific verb '修改' (modify) with the resource 'covered_course_ids 覆盖单' and clarifies it is the list of actually taught courses, not the license scope. This clearly distinguishes it from sibling tools like update_contract_cadence or complete_contract.

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 explicitly states that completed contracts (completed_at non-null) are rejected and directs users to open a new contract to continue teaching, providing an exclusion and alternative behavior. It implies usage for active contracts, though it does not name sibling tools directly.

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