find_modulation

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

The readOnlyHint annotation already tells the agent this is a safe non-mutating analysis call. The description adds value by enumerating the analysis dimensions and the named modulation types (pivot, ii-V, chromatic mediant, etc.), which compensates somewhat for the absent output schema, but says nothing about result format or whether one route is ranked.

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?

One front-loaded sentence with no filler. The parenthetical list of route types is dense but each item earns its place by signaling the tool's output vocabulary; only the truncated opening ('How to change key:') is slightly awkward.

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 usefully names what the analysis returns (closeness, pivot chords, route types) and both required parameters are schema-documented. It stops short of describing ordering ('smoothest to most dramatic' is mentioned, which helps) but format/pagination details remain unspecified.

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%, with both from_key and to_key documented and exampled in the schema. The description implies a pair of keys but adds no format or constraint detail beyond what the schema already provides, so the baseline 3 applies.

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 states a clear purpose - computing how to change key between two keys - and enumerates the specific dimensions returned (key closeness, shared pivot chords, chord routes). It is clearly distinct from theory siblings like reharmonize or suggest_progressions, though it does not explicitly name 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?

Without a stated verb or scenario, usage is only implied: you would call it when planning a key change. There is no explicit when-to-use or when-not-to-use guidance relative to reharmonize, analyze_progression, or suggest_progressions, all of which live in the same harmonic-analysis neighborhood.

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