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

Annotations already declare this is a non-read-only, non-destructive, closed-world mutation. The description adds genuinely new behavioral context: the audit side effect ('Records who changed it and when') and a configuration prerequisite. It doesn't say what happens if both seats_taken and delta are supplied, or what occurs if a delta pushes the count out of range, which keeps it from a 5.

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?

Two compact sentences, each carrying distinct information (modes, audit behavior, prerequisite), with the core operation front-loaded. No 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 three-parameter mutation with no output schema, the description covers purpose, modes, audit trail, and a prerequisite. Missing only edge-case behavior (both params given, out-of-bounds results), which is a minor gap.

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 100%, and the schema already describes id, seats_taken (0-500), and delta ('Or a step, e.g. 1 or -1'). The description largely restates those semantics rather than adding new meaning, such as whether the two value parameters are mutually exclusive or which wins.

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 names a specific verb ('Set') and resource ('seats taken in a class'), and immediately clarifies the two modes (absolute value via seats_taken, or a step via delta). This is clearly distinguishable from siblings like get_class or save_class, though it doesn't explicitly name an alternative.

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 states the two usage modes clearly and adds a precondition ('Needs the seats tick at its branch') that tells an agent when the call will fail. There are no explicit exclusions or named alternatives, but the context for correct use is well established.

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