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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), and the description goes further by disclosing optimistic-concurrency behavior: a stale expectedRevision is rejected to prevent clobbering another edit. That is exactly the kind of conflict/overwrite semantics an agent cannot infer from the annotations.

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?

Three compact sentences, each earning its place: overwrite behavior, required credentials, and stale-revision guard. The most decision-relevant fact (replacement) is front-loaded.

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 non-idempotent mutation with 11 required/optional params, a nested game object, and no output schema, the description covers auth and concurrency well but leaves most field semantics and the post-revision state (does it return the new revision number?) unaddressed. Adequate but with clear gaps.

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% across 11 parameters, so the description must carry the meaning. It only explains managementToken and expectedRevision (and the expectedRevision rule); fields like theme, occasion, message, recipient, sender, and recipientEmail are left entirely to inference from their names.

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?

Specific verb ('Replaces') plus resource ('an existing private draft with supplied HTML and game details') immediately distinguishes this from the sibling create_custom_game. An agent can tell revise vs create apart from the first sentence alone.

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 states the preconditions for use, namely that the draft's management token and current revision number are required, which tells the agent this only applies to an already-existing draft. It does not, however, explicitly contrast with create_custom_game or name the condition that selects one over the other.

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