list_sections

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

Annotations only declare read-only/open-world, so the description adds the substantive behavior: the shape of each entry (heading, line number, line count), the empty-list outcome for pre-1990 RFCs, and the cost signal ('cheap'). It also interprets its own output (a few hundred lines is a normal read; four figures wants a subsection or max_lines cap), which is genuine guidance an agent could not get from 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-loaded with the verb and return shape, then usage, then output interpretation, then the edge case. Every sentence carries information an agent needs; nothing repeats the schema or annotations.

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 still conveys the return shape, the empty-result case, and how to proceed from the result into get_rfc. For a single-parameter listing tool this covers everything needed to call it and act on its output.

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?

Only one parameter and schema description coverage is 0%, so the description must carry the load. 'An RFC's numbered headings' implies the parameter is an RFC number, but it never names it or resolves the anyOf ambiguity between integer and string forms (e.g. '1234' vs 'RFC 1234'). Adequate but leaves a real gap.

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 (list an RFC's numbered headings) plus exactly what each entry carries: line numbers and line counts. That is immediately distinguishable from siblings get_rfc (reads content) and search_rfcs (search), and no schema inspection is needed.

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?

Explicitly says it is the right first call when you need part of a spec, names the alternative path (pass the section to get_rfc), and gives a fallback for the case it cannot serve: pre-1990 RFCs return an empty list, so use get_rfc's line range. When-to-use, when-to-skip and the alternative are all stated.

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