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

Annotations already declare readOnlyHint and openWorldHint, yet the description adds the non-obvious trait that most courses return available=False with an explanatory message, which prevents an agent misreading an empty-looking result as an error. It doesn't touch permission requirements or result variability across courses, so it stops just short of full behavioral coverage.

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 core capability is front-loaded in the first sentence and the fallbacks follow without filler; every clause earns its place. The parenthetical about available=False is slightly dense but carries real information.

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 single-parameter read tool with an output schema already covering return structure, the description supplies the only things that could be missing: applicability condition, expected common negative outcome, and routing to alternatives.

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 the course_id field already explains the numeric PLATO/Moodle id and where to obtain it (list_courses). The description adds nothing further about the parameter, 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 (get) and a precisely scoped resource (account-level course-completion status) rather than generic course data. It explicitly separates itself from the two nearest siblings (get_activity_completion_status and get_course_contents' per-module flag), so an agent can pick the right tool without opening any 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?

Gives both a precondition (the course must have course-level completion criteria) and the fallback path, naming the exact alternative tools for the common case where criteria don't exist. There is essentially no ambiguity about when to call this versus its siblings.

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