estimate_before_design

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

Annotations already establish this as a safe, non-destructive, non-open-world read, so the description only needs to add estimation behavior. It does: it discloses that the estimate is computed analytically from dimensions (no slicing/generation), that multi-material runs get per-filament usage plus automatic tool-change overhead, and it enumerates the returned fields (per-filament weight/length/cost, electricity, total, swap count) despite there being no output schema.

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 well: purpose, then the two dimension modes, then multi-material, then return values — a sensible order. But roughly half the body is a ':param' list duplicating a schema that already has 100% description coverage, and 16 parameters make the whole thing long enough that the useful behavioral content competes with 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 16-parameter, zero-required-parameter tool with no output schema, it covers the important gaps: what is returned, how the two dimension modes interact, how multi-material fractions/roles work, the auto-sentinel values (-1 infill, 0 layer height, unset nozzle), and it points to list_multi_material_addons for the addon enumeration. The only real omission is guidance on which printer_id values are valid.

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 already 100%, and the ':param' block is largely a verbatim restatement of the schema text, so most of it earns no credit. The genuinely additive part is the framing of the two mutually exclusive input modes (explicit width/depth/height vs. template_id with template_overrides taking precedence), which clarifies an OR-relationship the flat schema cannot express.

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 (estimate print time, cost, filament usage) plus a decisive scope qualifier: 'BEFORE generating a model' and 'works from dimensions alone — no file, no slicing, no generation needed.' That qualifier is exactly what separates it from mesh-based siblings like estimate_mesh_print_time, estimate_print_cost_from_mesh, and slice_and_estimate.

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 concrete triggering questions ('how long will it take?', 'how much will it cost?') and a clear precondition (before committing to a design), and the two-way dimension specification is spelled out. It stops short of naming the alternative tools to use when a mesh already exists, so the agent must infer the boundary rather than being routed to it.

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