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

Annotations already cover read-only, idempotent, and open-world traits, so the bar is lower. The description still adds real context beyond them: the per-call price of $0.001 USDC via x402 on Solana and an equivalent HTTPS endpoint, plus spelling conventions (letters stay in thirds except suspensions and the sixth; dim7 may use a double flat) that tell the agent what the output will look like.

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?

It is front-loaded with the operation and the quality list, followed by only the spelling rules and payment details that an agent actually needs. Slightly dense, but no sentence is dead weight.

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 and only two parameters, the missing piece is what the return value looks like — presumably a sequence of spelled note names, but that is never stated, nor is the accepted note-input syntax. The payment/endpoint coverage is thorough, so this is an incomplete rather than an inadequate definition.

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%, so the description must carry parameter meaning. It explains the 'quality' side well by listing all twelve spellings, matching the enum, but it says nothing about the accepted format for 'note' — octave required or not, case sensitivity, flat/sharp syntax — despite the 16-character maxLength suggesting flexibility. Partial compensation only.

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?

The description opens with a specific verb and resource: 'Spell a chord up from a root', then enumerates the twelve supported qualities. It is unambiguous on its own, but it never names or distinguishes itself from the nearby music_scale, music_interval, or music_transpose siblings, so an agent must infer the split.

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 by the operation itself: give a root note and a quality, get a chord spelling. There is no statement of when to prefer this over music_scale (build a scale) or music_transpose (shift a pitch), and no exclusions or prerequisites beyond the price note.

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