Log a dated play session

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

Annotations already indicate this is a non-destructive (destructiveHint=false) and idempotent operation. The description adds that existing sessions and shelf state are preserved, reinforcing the non-destructive nature, and clarifies the dependency on an existing playthrough. No contradiction with annotations, and the added context is useful.

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, front-loaded with the main action, followed by essential context. Every word earns its place, and the structure is easy to scan.

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 mutation tool with no output schema, the description provides sufficient context: what it does, the playthrough prerequisite, and non-destructive behavior. It doesn't detail every parameter or return value, but the schema covers those, and the tool's purpose is clear.

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 75%, so the description doesn't need to explain every parameter. It adds meaning by summarizing the core purpose (date, duration, note) and explicitly connecting playthrough_id to existing playthroughs. This complements the schema without redundant repetition.

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?

The description uses a specific verb ('Record') and clearly identifies the resource (a play session) with its scope (particular date, optional duration and note). It further distinguishes itself from siblings by noting it attaches to an existing playthrough and pointing to get_play_sessions for IDs, making the purpose unmistakable.

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?

The description gives clear context on how to use it: you need an existing playthrough, and get_play_sessions provides the IDs. It implies this is for adding to an existing playthrough rather than creating a new one, though it doesn't explicitly state when not to use it or name alternative tools. This is sufficient guidance for most cases.

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