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

readOnlyHint=true and openWorldHint=true already tell the agent this is a safe read against external data, so the description's main addition is the efficiency claim of direct resolution. It does not mention failure behavior for an invalid cmid, course scoping, or that the lookup is a remote round trip.

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?

One short sentence with the resource and constraint front-loaded; the trailing clause about not fetching the whole course earns its place as differentiation. It could be tightened slightly without losing meaning.

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 one-parameter, annotated, read-only lookup with an output schema, the description covers what the agent needs to decide and invoke. Only edge-case behavior such as invalid or out-of-course cmids is left unstated.

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% with a single documented 'cmid' parameter, so baseline is 3. The description reinforces that the id identifies one module but adds no format, scope, or validity detail beyond the schema.

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?

Names a specific verb ('Resolve') and resource ('a single course module'), plus the identifying key ('by its id'). It implicitly sets itself apart from get_course_contents by contrast ('without fetching and filtering the whole course's contents'), though it never names that sibling explicitly.

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 makes the selection condition clear: call this when you already have a cmid and want one module, rather than pulling an entire course and filtering. It doesn't state what to do when the cmid is unknown or cross-course disambiguation is needed, so no explicit exclusions.

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