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

Annotations already pin down the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description still contributes by disclosing the accepted input dialects, the muted/open conventions, and the fact that it returns notes and a diagram rather than just a name. It does not mention failure behavior for unplayable fingerings, which keeps it from 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 sentences, zero padding; the purpose and outputs come first, then the concrete invocation condition with examples. Every clause 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 single-parameter, schema-complete, annotation-rich tool with no output schema, the description covers what it returns (name, notes, diagram) and how to phrase the input. Nothing an agent needs in order to call it correctly is missing.

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 would be 3; however the description adds value by restating the low-E-first ordering alongside the schema and by showing the space-separated dialect ('0 2 2 1 0 0') in a natural-language sentence, reinforcing that separators are flexible. It stops short of stating the valid fret range or how many frets are required beyond the schema's own wording.

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 pair ('Names the chord a guitarist is holding'), and explicitly enumerates the three outputs: chord name, constituent notes, and a chord diagram. It is the inverse of the sibling get_chord_shapes (which returns shapes for a named chord), and the phrasing makes that direction 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?

Gives an explicit trigger: 'Use when someone asks "what chord is this?" and gives frets like x32010, 3-2-0-0-0-3 or "0 2 2 1 0 0"'. No exclusionary guidance is offered against alternatives such as get_chord_shapes or find_key, but the usage condition is concrete enough that an agent can route correctly.

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