check_dimension_chains

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: it discloses that segments are summed and compared to the overall dimension, that units are metres, that no SketchUp session is needed, and gives an explicit conflict-handling rule ('show the user which one and ask which number wins; do not guess'). It never states whether it mutates anything, though the read-only nature is strongly implied by 'check'.

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, followed by a compact example and behavioral rules. Every element earns its place, though the conflict-handling sentence sits slightly apart from the rest of the flow.

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?

An output schema exists, so return values need no explanation. Combined with the explicit pre-modelling timing, units, dependency note, and conflict policy, the agent has enough to invoke it correctly. The only real gap is the undocumented tolerance parameter.

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%, so the description must compensate. It compensates for the required 'chains' parameter by showing the exact object shape (label, segments, total) and units. The optional 'tolerance' parameter (default 0.005) is never mentioned, so the coverage gap is only partially filled.

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: 'Check that the dimension strings on a plan add up,' with a worked example showing the chain structure. The purpose is unambiguous. It does not, however, distinguish itself from the sibling verify_dimensions, which an agent could reasonably confuse with it.

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 a clear temporal precondition ('BEFORE modelling') and notes it 'Does not need SketchUp,' which tells the agent this is a pure computation independent of the live model. It does not name an alternative tool or state when NOT to use it, so it stops short of the 5 tier.

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