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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds a genuine behavioral trait beyond the annotations: this tool is invoked only by the viewer, not by the assistant, which is exactly the context an agent needs to avoid misusing it. It stops short of describing failure modes or what the viewer does with the result.

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?

Two sentences, zero filler. The purpose is front-loaded and the restriction plus alternative follow immediately; every clause earns its place.

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 single-parameter read tool with no output schema, the description covers what is read (code files and tree hash) and who may call it. Return-shape details are arguably unnecessary here, though a brief note on error behavior when the forge is missing or the viewer has no session would round it out.

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% and the single forgeId parameter is well documented in the schema (id or slug, as returned by list_forges or get_forge). The description adds no syntax or format detail beyond that, so the baseline of 3 applies.

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 precise verb and resource — reads a forge's code files and tree hash for the PartForge viewer to build and display it. It also distinguishes itself from the assistant-facing sibling by naming read_part_files, so the agent can route correctly without opening a 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 an explicit when-not ('Only the viewer calls this; it is not a tool for the assistant') and names the alternative to use instead ('use read_part_files instead'). Nothing about tool selection is left to inference.

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