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

Annotations already mark destructiveHint=true, and the description adds the specific destructive behavior: 'Overwrites the spec file.' It also discloses the skip behavior for the V/S/T chain when actionItemId or a freeform description is passed. This goes beyond the generic annotation without contradicting it.

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?

The description is front-loaded with the core purpose and resource path, then lists the spec contents, then the overwrite behavior, then the input shortcut, then the alternative tool. Every sentence carries distinct information and there is no filler or 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?

For a tool with 10 parameters, nested objects, and no output schema, the description covers the essential decision points: what is generated, where, what it contains, that it overwrites, how to choose input mode, and when to use the sibling tool. It does not describe return values, but the generated file path is stated, so the main output is clear. Minor gaps remain around the meaning of the V/S/T chain, but the schema covers the remaining parameters.

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 baseline is 3. The description adds meaningful parameter semantics by explaining that actionItemId or a freeform description can be used to skip the V/S/T chain, which clarifies the relationship between those inputs. It does not repeat every parameter, which is appropriate given the schema already covers them.

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 names a specific verb ('Generate'), a concrete resource ('vdd/specs/<id>/spec.md'), and a clear scope ('for one tactical action item'). It also lists the spec contents (user stories, boundaries, AC, MoSCoW, NFRs, impact verification), which distinguishes it from sibling tools. The explicit 'Use for a NEW spec' and 'use vdd_clarify instead' further differentiates it from vdd_clarify.

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 description gives explicit when-to-use guidance: 'Use for a NEW spec'. It also names the alternative tool and the condition for choosing it: 'to resolve leftover [NEEDS CLARIFICATION] markers in an existing spec use vdd_clarify instead.' This is direct routing guidance with no ambiguity.

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