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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds value by disclosing what the payload contains — notably the lecture list with key concepts and URLs — which matters since there is no output schema. It says nothing about behavior for an invalid or unknown slug, though.

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?

One compact sentence with no filler, front-loaded with the most important returned fields. It is a fragment rather than a complete statement of purpose, which costs it a point.

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?

With no output schema, the description usefully enumerates the return payload, which is the main gap it needed to fill. For a simple two-parameter read tool whose annotations cover safety, only error/not-found behavior is left unstated.

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%: slug is documented as coming from search_courses and lang is documented with an ISO 639-1 enum and default. The description adds no parameter meaning beyond that, so 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?

The description is a noun phrase enumerating returned fields (description, audience, prerequisites, access terms, lectures) rather than stating a verb+resource. It implies a single-course detail lookup but never says so explicitly, and it draws no boundary against the siblings search_courses, get_guide, or search_guides.

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 mention that search_courses must run first to obtain a slug, and no exclusion of the sibling search tools. The only workflow hint ('Course slug from search_courses') lives in the schema, not the description.

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