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

The description discloses useful behavior (it overwrites tasks.md, it requires plan.md, feature must match the vdd_plan value), but it directly contradicts the annotations: it describes writing/overwriting a file while annotations declare readOnlyHint=true. This is an annotation contradiction of the same class as a 'creates' tool marked read-only, so the dimension scores 1 regardless of the otherwise-good disclosure.

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 action and artifact, and every sentence carries information (overwrite warning, prerequisite, alternative tool, parameter relationship). The first sentence is dense with output-format clauses (AC references, S/M/L sizing, [P] markers) that are useful but slightly crowded.

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 needn't explain return values, and it covers the remaining agent-critical facts: the write/overwrite side effect, the prerequisite phase, the sibling to use instead, and the parameter coupling to vdd_plan. Nothing needed to invoke it correctly is missing—though the write behavior conflicts with the annotations.

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 baseline is 3; the description goes beyond the schema by stating the cross-tool relationship 'feature must match the value passed to vdd_plan', which is not encoded anywhere in the property definitions. It does not add syntax or format detail beyond that, so it lands just above baseline.

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 artifact: break the plan into atomic test-first tasks written to vdd/specs/<feature>/tasks.md, plus phase placement (VDD Phase 6). It differentiates itself from siblings by naming vdd_plan as the prerequisite and vdd_get_next_task as the tool for a different job. 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 explicit sequencing ('Requires plan.md; run after vdd_plan') and an explicit when-not/alernative ('To fetch the next uncompleted task from an existing tasks.md use vdd_get_next_task instead of re-running this'). The conditions that select this tool versus its closest sibling are fully spelled out.

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