Edit binary SCF input stimulus directly

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

Beyond the destructive/idempotent annotations, it discloses that groups, other signal records, and opaque editor bytes are preserved, that a backup is taken before an atomic write, that expectedSha256 must be current, and that derived output/internal traces become stale and need re-simulation. That is exactly the side-effect detail an agent needs for a destructive mutation.

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?

Six tight, front-loaded sentences with no filler; the preview/apply distinction and the key constraints come first. The clipped telegraphic style occasionally costs readability but every sentence carries information.

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 destructive, non-idempotent edit with no output schema, the description covers preconditions (fresh SHA-256, scalar-only), side effects (backup, atomic write, stale traces), and the bus workaround. Coverage is strong; only the relationship to the sibling stimulus-edit tool is unaddressed.

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 100%, so the schema already documents path, edits, time ticks, values, confirm, and expectedSha256. The description restates the 0.1ns/0-1-X-Z constraints and the SHA-256 requirement rather than adding syntax or format detail beyond the schema, 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 gives a specific verb (edit), resource (SCF input stimulus), and scope (existing scalar inputs in vendor version-4 SCF), so the agent knows it mutates existing records rather than creating them. It distinguishes the scalar-only scope clearly, though it never explicitly separates itself from near-neighbor siblings like scf_stimulus_edit or scf_structure_edit.

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?

It gives actionable guidance: use scf_inspect to find scalar members for a bus and edit those instead of the bus directly, and it states the SHA-256 precondition. It stops short of naming the sibling alternative (scf_stimulus_edit) for cases where this tool is the wrong choice.

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