Describe variable names: grammar, units, QC and sites

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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so safety is covered; the description adds the 20-name practical cap and the exact facets returned per name (QA/QC range, QC meaning per resolution, sign conventions, site instrument/height/coverage). It says nothing about behavior on unrecognized or malformed names, which is the notable remaining gap.

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 the 20-name scope, then the decoding facets, then the site behavior and the next-step pointer. Information-dense and largely tele grams-style, with the only cost being the compressed comma-spliced listing that takes a second pass to parse.

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 an output schema present and annotations covering the safety/idempotency profile, the description need not restate return structure, and it covers all three parameters plus the workflow handoff. The one omission is failure/partial-match behavior for unknown names, which matters when passing arbitrary file headers.

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%, so baseline is 3, but the description goes beyond it by explaining the name grammar itself with concrete token families (_PI, _QC, _F, _IU, _H_V_R, MDS, VUT/CUT, NT/DT, REF, percentiles) and by clarifying what 'site' unlocks. That materially helps an agent build valid 'names' values rather than just reading the schema.

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?

Specific verb 'Decode' plus a precisely scoped resource: up to 20 variable names from BASE or FLUXNET files, with an enumerated list of what gets decoded (base name, FP Standard definition, qualifiers, position tokens, units, QC, sign conventions). This clearly separates it from the sibling amf_search_variables, which finds names rather than explaining them.

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?

The framing 'Decode ... from BASE or FLUXNET files' plus 'With site: whether the site measures it...' makes the use context clear, and 'Next: call amf_get_availability for the site's years' gives an explicit follow-up step. It stops short of naming when to use amf_search_variables instead, so no true alternative routing.

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