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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-derivable context: it does not edit artifacts, it returns a plan and the host agent applies edits and commits, and the return is an ordered step list naming gates rather than rewritten artifacts. It stops short of describing failure modes or partial-plan behavior, so not a 5.

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-loaded with the core purpose, then output semantics, then usage routing, then parameter relationships. Dense but every clause carries information; the only mild redundancy is restating the read-only/plan-only nature twice, which is defensible given it is the key behavioral trait.

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, the description need not enumerate return fields, and it appropriately summarizes the return shape (ordered step list naming gates). Combined with annotations covering safety and idempotency and 100% schema coverage, nothing an agent needs to call this tool correctly is missing.

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 parameter descriptions already carry the load (baseline 3). The description still adds relational meaning the schema does not: 'description is the requirement change to cascade' and 'projectRoot must match the root used by earlier phases', which is a cross-phase constraint not captured per-field.

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 and resource ('Plan a requirement-change cascade through the whole chain'), names the concrete output (ordered steps V→S→T→SP→PL→TK and affected gates G1–G7), and explicitly contrasts with the sibling pattern of running a phase's own tool. An agent can identify this tool without opening any schema.

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?

Gives an explicit trigger ('Use when a requirement changes after artifacts already exist') and an explicit exclusion with the alternative ('to build a phase from scratch the first time, run that phase's own tool instead of vdd_amend'). This is textbook when/when-not guidance.

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