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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world, so the safety profile is covered. The description adds real value beyond that by disclosing the shape and breadth of the payload, notably that it includes linked tasks, what the lesson was applied as, and earlier versions. It stops short of noting behavior for a missing/invalid ref, but it meaningfully exceeds the annotation baseline.

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?

A single front-loaded sentence that leads with the operation and ref, then lists the returned fields without filler. It is dense but every clause describes actual returned content; only the trailing enumeration makes it slightly run-on.

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 carries the return-value burden and does so by naming the key fields (narrative, status, linked tasks, applied-as, versions). Combined with annotations covering the read-only/idempotent profile, an agent has enough to call it correctly. Only error/not-found behavior and ref validation are unaddressed.

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?

There is one parameter (ref) with 0% schema description coverage, so the schema gives no format guidance. The description partially compensates by showing the expected identifier shape, 'ref (LES-004)'. It does not say whether the ref is case-sensitive, what happens on an unknown ref, or whether any other identifier form is accepted.

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: fetch 'one lesson by ref', and enumerates exactly what that lesson record contains (what happened, what we learned, status, linked tasks, applied-as, earlier versions). This clearly separates it from list-style siblings like fenbs_list_lessons. It does not explicitly name a sibling, but the singular 'one lesson by ref' framing makes the scope unambiguous.

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?

Usage is only implied: an agent should call this when it already holds a lesson ref and wants the full record, as opposed to fenbs_list_lessons for enumeration. There is no explicit when-to-use statement, no mention of prerequisites (e.g. needing a valid ref), and no named alternative. Adequate but with a clear gap.

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