Course file

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

Discloses the full outcome matrix — text/HTML returned as readable text, PDF with text extracted, PDF without text or unsupported types falling back to file name plus a redacted link and a Moodle note — which annotations (readOnlyHint, openWorldHint) do not cover. The security note that only links on the school's Moodle site are downloaded, so the key is never sent elsewhere, is valuable context beyond structured fields. No contradiction 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?

Front-loads the core question and action, which is good, but repeats the same fallback clause ('file name, a link with your key removed and a note to open it in Moodle') three times and states supported types twice. The redundant sentences dilute an otherwise well-organized description.

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 no output schema, the description covers the input's provenance, all supported and unsupported outcomes, the security boundary, and a usage example. An agent has everything needed to call it and anticipate what comes back.

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 required parameter, so the baseline is 3; the description adds real value by specifying the parameter's origin ('the link from get_course_content') rather than any arbitrary URL. It does not add constraints such as whether the URL must be absolute or a Moodle-relative path, keeping it below a 5.

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 ('Downloads one course file resource, such as a PDF, slide deck or handout') and anchors it to a concrete user question. It implicitly distinguishes itself from get_course_content, which supplies the link rather than the content, so an agent can route between them without opening either 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 clear context ('Answers what does this course file say?'), names the upstream source ('the link from get_course_content') and provides a worked example ask. It stops short of an explicit when-not-to-use statement, e.g. 'use get_course_content to list files and this to read one,' but the sourcing instruction makes the split inferable.

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