build

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

With no annotations, the description carries the full burden and does well by disclosing non-activation, success output (store path), and failure payload (failed_derivation with drv and log_tail). It does not mention store side effects or mode behavior, but the core behavioral traits are covered.

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 two sentences, front-loaded with the action and object, and contains no filler. Every sentence adds value: purpose, output, and failure behavior.

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?

The description adequately covers purpose, output, and failure modes, and an output schema likely covers return values. However, parameter semantics are entirely missing, and there is no explicit guidance on how this differs from 'switch' beyond 'without activating it', leaving the description incomplete for effective tool selection.

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 0% and the description never mentions 'mode' or 'flake_uri'. The agent gets no additional meaning beyond the parameter names and defaults, leaving significant ambiguity about valid values and their purpose.

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 clearly states the tool's purpose with a specific verb ('Build'), resource ('full system/HM closure'), and key scope ('without activating it'). This distinguishes it from activation-related siblings like 'switch'.

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 phrase 'without activating it' gives clear context for when to use this tool (pre-activation/build-only), and the mention of 'output store path' suggests inspecting build results. However, it does not explicitly name alternatives or state when not to use it.

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