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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds meaningful behavior beyond them: answers are hidden exactly as for students, diagnostics are not previewable, and it signals low cost ('Cheap'). These are genuine operational facts an agent should know before calling.

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?

Front-loaded with the core behavior and kept to one tight sentence plus a terse cost hint. 'Cheap.' is a fragment, but it carries a real signal and everything 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?

An output schema exists, so return-value explanation is unnecessary, and the description supplies the key behavioral caveats (hidden answers, no diagnostics preview). Only the missing sibling routing keeps it from being fully complete for a one-param read tool.

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%, and assignmentId's meaning (id from list_coursework) is fully documented in the schema. The description adds no parameter detail, 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 ('what a student will see when they open the assignment') and enumerates the returned content (instructions and each section in order). The 'as a student' framing implicitly separates it from the teacher-facing get_assignment sibling, so an agent can pick it without opening a schema.

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?

Usage is implied by the preview framing, and it notes one boundary ('Diagnostics can't be previewed'), but it never names an alternative (e.g., get_assignment or preview_question) or states when to choose this tool over them. Adequate but with a clear routing gap.

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