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

Annotations already declare this is a non-read-only, non-idempotent, non-destructive local write, so safety is covered. The description adds a genuinely behavioral fact beyond that: the pact is "not enforced; keeping it is up to you," telling the agent that accepting creates no binding obligation — context it could not get from structured fields.

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 short sentences, zero padding, with the action and the source of the id front-loaded and the non-binding caveat second. Nothing to trim.

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 two-parameter, low-complexity game action with no output schema, the description is nearly sufficient, but it omits what happens on success/failure (does the pact become active, what does the tool return?) and any error conditions such as an unknown pact id or an ended session.

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 50%: `session_id` is documented as coming from `start_game`, while `pact_id` has no description. The description compensates partially by saying the pact number appears in the game text, which is the only guidance an agent has for sourcing that id, but it adds no format or validity constraints beyond the schema.

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 + resource ("Accepts a pact another player proposed in this game"), with the scope narrowed to the current game. It doesn't reference the sibling `propose_pact`, so the agent must infer the pairing, but the action itself is unambiguous.

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?

Implicit usage: you would call this when another player proposed a pact and you want to take it. The description hints at where to find the pact id ("its number is in the game text"), but never names alternatives such as `propose_pact` or states preconditions like whether the game must still be active or whose turn it is.

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