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

Annotations declare readOnlyHint=true, so the safety profile is already covered. The description compensates by disclosing the return content (deep link plus booking method), which is meaningful given there is no output schema. It omits auth requirements or failure modes, so it is not a 5.

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?

Two short sentences, zero filler, with the resource and return payload front-loaded ahead of the usage instruction. Every sentence 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?

For a simple one-parameter read tool with no output schema, the description covers purpose, expected return content, and the user-facing action. The only real gap is that the slug's origin/format is left to the schema, which is undocumented.

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 0%, and the single parameter "slug" is never mentioned by name or format. The phrase "for a course" implicitly identifies what the slug refers to, which is partial compensation but leaves the agent inferring the identifier's meaning and shape.

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+resource: it returns the official booking deep link and the booking method (online/phone) for a course. An agent immediately knows this is a retrieval tool for booking URLs. It does not explicitly name the siblings get_course or search_courses to differentiate scope, which caps it at 4.

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?

"Send the user here to book" gives a clear, actionable when-to-use cue tied to the user's booking intent. There is no explicit when-not guidance or comparison against get_course (e.g., use that for details, this for the booking action), so it stops short of 5.

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