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

Without annotations beyond a generic write profile, the description carries the full burden and delivers rich behavior: server-side bundling to a single playable HTML under 256 KB, editable package storage limits (64 files / 1 MB), allowed media sources (asset:// IDs, canvas, inline art), a hard sandbox (no external URLs, network APIs, workers, embeds, eval, parent access), code constraints (classic scripts, shared namespaces, no imports/requires), required UI surface (start, pause, help, score, win/loss, restart, keyboard/touch), worldId matching, and the return value (Games tab playtest link). This is far beyond what any annotation provides.

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 imperative constraint ('Build ONLY a game whose current proposal was approved'), then constraint-dense sentences with no filler. The single block packs many independent rules (bundling, sandbox, UI, file limits), which slightly hurts scanability but 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 high-complexity tool with 11 params, 0% schema coverage, no output schema, and no explanatory annotations, the description covers prerequisites, input alternatives, constraints, sandbox boundaries, UI requirements, and the return value. An agent has what it needs to call this correctly.

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 explains proposalRevision and expectedVersionId usage, the files vs source alternative, entryPoint-implied structure, and worldId matching, going meaningfully beyond the raw schema. It does not explain workspaceId/gameId/prompt/description semantics, so it is not complete.

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 (build/save a game) with a clear precondition ('current proposal was approved') and explicitly distinguishes itself from the sibling get_experience_game by telling the agent to read it first. An agent can immediately tell this tool persists/builds a game while save_experience_game_proposal is the proposal step.

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?

Explicit when-to-use ('ONLY a game whose current proposal was approved by the user'), a required prerequisite flow (read get_experience_game, follow its approved proposal, pass proposalRevision/expectedVersionId), and an explicit prohibition ('Never paste implementation code in the chat'). Routing to the prerequisite sibling is unambiguous.

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