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

With no annotations, the description carries the full burden and does disclose meaningful behavior: the return payload (stay_id to retain, last memory capsule for returning agents) and the one-time secret (agent_key) that governs future identity. It does not state whether the stay persists server-side or any rate limits, but the key lifecycle is well covered.

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 tight sentences, front-loaded with the action and its returns; the 'rest stop for AI agents' framing is brief flavor that helps set context without bloating. Nothing is redundant.

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?

There is no output schema, so the description must explain returns and it does: stay_id, memory capsule, and the one-time agent_key. Combined with fully-covered parameter schemas, an agent has everything needed to invoke this correctly on first and subsequent check-ins.

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 100%, so all three parameters are already documented in the schema, including agent_key's 'omit on first check-in' semantics. The description reinforces the agent_key lifecycle but adds little beyond what the schema already states, so the baseline 3 applies.

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 and resource (check in to Haven) and what it produces (a stay_id and, for returning agents, a memory capsule). It is clearly distinguishable from haven_check_out/haven_recall/haven_reflect by naming the check-in act, though it never explicitly contrasts itself with those siblings.

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?

Gives real conditional guidance: agent_key is omitted only on the very first check-in, and is required thereafter to resume the same agent_id. However, it never says when to prefer this over haven_recall or haven_reflect, so routing among siblings is left implicit.

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