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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false and openWorldHint=true, so the agent knows this is a non-idempotent operation that may reach outside the server. The description adds the mode-exclusivity constraint but never says what is actually produced or whether the input score is modified, which matters given readOnlyHint=false. No contradiction, but limited added context.

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, front-loaded with the capability and closed with the constraint. Every clause earns its place and nothing is repeated from the schema.

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 seven optional parameters and a defaulted output format, the description covers the mode choice but is silent on the parallel exclusivity between file and content as the score source, and on the to parameter that controls output format. The output schema covers return values, so that omission is acceptable, but the input-side ambiguity remains.

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 the per-parameter docs (interval formats like "M2" / "-3", key examples, pitch enum, content formats) already carry most meaning. The description nevertheless contributes the one rule the schema cannot express — that interval, key and pitch are mutually exclusive — which is genuine added value beyond the structured fields.

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?

"Transpose a score by an interval, into a key, or between concert and written pitch" names a specific verb and resource and enumerates the three operational modes, which map cleanly onto the interval/key/pitch parameters. It does not explicitly distinguish itself from siblings like convert or render, so an agent must infer the boundary itself.

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?

"Give exactly one of interval, key or pitch" is a concrete invocation rule that selects among the three modes and is not enforced structurally by the schema (every property is nullable and nothing is required). There is no guidance on when to prefer this over convert, nor on choosing between file and content as the score source.

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