diff_comp

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

readOnlyHint=true already establishes this is a safe read, so the bar is lower. The description adds real value beyond the annotation by disclosing the prerequisite dependency and the exact nature of the output (added/removed nodes, changed knobs). It stops short of describing edge cases such as what happens with an invalid or stale snapshot_id.

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?

Front-loads the purpose in one tight sentence, then the prerequisite, then the arg. Efficient overall, though the Args block restates what the schema already documents, which is mild redundancy.

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 an output schema present, return values need not be explained, and the readOnly annotation covers the safety profile. The prerequisite and diff contents make it callable as-is; the only gap is not relating it to the other diff-like siblings in the toolset.

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% and the single parameter's description already reads 'ID from a previous snapshot_comp call'. The description repeats this verbatim, adding no syntax, format, or validity constraints beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 (compare/diff) and resource (current comp vs previous snapshot), and enumerates exactly what the diff surfaces (nodes added, removed, knobs changed). This distinguishes it clearly from sibling snapshot_comp, which creates rather than compares snapshots.

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?

Explicitly gives the prerequisite 'Call snapshot_comp first', which tells the agent the correct ordering and which tool must precede it. It does not, however, mention when to prefer it over related siblings like scene_delta or scene_digest.

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