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

Annotations already establish readOnly, idempotent, non-destructive behavior, so the safety profile is covered. The description adds the cost hint ('Cheap.') and hints at breadth of return, but omits behavior on missing/invalid ids or what 'student links' resolve to. A modest addition beyond the annotations.

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 sentences, front-loaded with the payload description and closing on the one differentiating cost signal. Nothing is wasted, even the fragment 'Cheap.' carries routing value.

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?

Because an output schema exists, the enumeration of return fields is largely redundant, and the description compensates with no usage routing or error behavior. It is adequate to invoke the tool but leaves the when/why gaps unfilled.

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?

With a single parameter at 100% schema coverage, the schema fully documents assignmentId (including its origin in list_coursework). The description adds no format, validity, or fallback detail beyond it, so the 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 and resource (get one assignment) and enumerates what it returns: sections, question counts, scoring/timing settings, published classes, due dates, student links. This distinguishes it well from thin siblings like get_assignment_status or get_assignment_question_breakdown, though it never names those siblings 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?

There is no when-to-use guidance, no prerequisites, and no named alternative. The trailing 'Cheap.' is the only routing signal, hinting the agent should prefer this over costlier calls, but the agent must infer the rest.

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