als_diff

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

Annotations already declare readOnly=true, destructive=false, openWorld=false, so safety is covered. The description still adds real behavioral value by disclosing the implicit backup-resolution behavior when new_path is omitted — a non-obvious side effect the agent could not infer from the schema. It does not mention error behavior or output shape, but an output schema exists.

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 comparison scope, then the special one-argument mode. The long comma-separated enumeration is dense but earns its place by telling the agent what evidence a diff contains. No filler or restatement of the title.

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 read-only, two-parameter diff tool with an output schema and safety annotations, the description covers what is compared and the fallback resolution mode — the essentials an agent needs. Minor gaps remain around failure modes and how the two paths must relate (e.g., same project vs. arbitrary versions).

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 the parameter meaning, and it partially does: it explains that old_path is the base version and that supplying only old_path triggers the Backup-folder lookup for the 'new' side. It leaves the exact path format (filesystem path to a .als file) and what happens with a relative path unstated.

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?

Names the specific operation (diff two versions of a Live Set .als file) and enumerates exactly what is compared: tempo, track add/remove/rename, fader, mute, routing, devices, clips and note counts, locators, scenes, plug-ins. That is far more specific than the name alone. It does not, however, distinguish itself from similarly-named siblings such as session_diff, als_summary, or als_lint.

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 second sentence gives a genuine usage rule for the single-argument mode (old_path only resolves the newest Backup copy as the old side). But there is no guidance on when to choose this over session_diff or als_summary/als_lint, and no stated preconditions such as both files needing to be valid .als files.

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