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

Beyond the readOnly/idempotent annotations, the description discloses pagination semantics (partial completeness, range, nextCursor), error cases (invalid_cursor, module_not_found), a hash for integrity, and a prompt-injection caution that the text is data, not instructions. This is unusually rich and fully consistent with 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?

The description front-loads the action and then presents dense, non-redundant behavioral details in a logical order: output shape, pagination, errors, then safety. No sentence is filler, and the length is justified by the complexity of the pagination behavior.

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?

Given that an output schema exists and annotations cover safety, the description covers everything an agent needs: return format, metadata, pagination, cursor continuation, error responses, and the security boundary around lesson content. There are no obvious gaps that would cause an incorrect call.

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?

The schema already documents all four parameters at 100% coverage, so the baseline is 3. The description adds value by explaining cursor behavior across revisions, fragment boundaries at 40,000 characters, and how the hash relates to the full document, which helps an agent use cursor and maxChars correctly.

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 opening 'Use to read one lesson' names a concrete verb and resource, and the rest clarifies it returns the module text as Markdown with metadata. However, it never explicitly names a sibling tool (e.g., getCourseModules or searchContent) as the alternative, so sibling differentiation is implicit rather than explicit.

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 phrase 'Use to read one lesson' provides a clear reason for invoking this tool, and the note that module accepts an id/slug from getCourseModules hints at the listing prerequisite. It does not, however, state when to prefer alternatives like searchContent or getCourseDetails, so there are no formal exclusions.

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