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

With annotations already covering safety (readOnlyHint=false, idempotentHint=true, destructiveHint=false), the description still adds substantial non-structured context: re-publishing replaces all hosted files while the link/slug stays fixed, the 100-file / 5 MB limits, the key-ownership enforcement rule, and the visibility model ('nothing is listed publicly; only people with the link find it'). The one nuance is that a link open to anyone sits in slight tension with openWorldHint=false, but since the origin is platform-controlled this is a scope judgment, not a contradiction.

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 outcome (the share URL) before mechanics, and nearly every sentence adds operational information: paths, encoding, key ownership, re-publish semantics, limits. It runs long and a few clauses ('paths relative to it', the parenthetical about how the server knows the build belongs) restate schema content and could be trimmed.

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 write tool with no output schema this is close to complete: it covers inputs, the key-ownership precondition, size/count limits, idempotent replacement behavior, and post-action instructions (hand the URL to the user). The only omission is what the call returns on success or failure, which is a minor gap for a publish operation.

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 coverage is 100%, so the baseline is 3; the description earns above that by explaining the 'game' parameter's real semantics — it identifies which game the build belongs to and a mismatched key is actively refused — which the schema does not convey. It also restates the utf8/base64 split for 'encoding' and relative-path convention, but those largely duplicate existing schema descriptions.

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?

A specific verb (host/publish) applied to a specific resource (the game's files) with the exact resulting artifact spelled out: a public share link at https://<slug>.play.multiplayeragent.com/. It is unmistakably distinct from siblings like create_game, set_game_name, or get_connection_info, so an agent can route here 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?

It gives clear situational guidance: send every file the game needs, re-run after every change, and give the user the URL. The prerequisite (files must carry this game's publishable key or the server refuses the build) is stated explicitly. What's missing is any explicit exclusion or named alternative — e.g. what to do before a game exists or how this relates to get_client_snippet — so it stops just short of a 5.

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