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

With no annotations, the description carries the full burden. It usefully discloses the two-stage lifecycle ('paid' vs 'credited') and that account_key only becomes actionable once credited, but it omits whether the call is read-only and side-effect free, how pending or unknown deposit_ids behave, and whether repeated polling is safe or rate-limited.

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 with zero filler. The core check is front-loaded, and the downstream hand-off sentence comes second, so an agent gets the primary purpose before the routing advice.

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 has to convey what comes back, and it does name the three pieces of information (paid, credited, credits added). It stops short of enumerating possible status values or failure cases for an unknown deposit_id, which is the remaining gap for a lookup tool with no annotations.

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% and both parameters are already documented, including that deposit_id comes from create_deposit. The description only adds that account_key is the value to reuse with create_inbox or send_message, which is a small but real semantic addition over the schema; 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?

Names a specific verb ('Check') and resource ('deposit'), and states exactly the two facts returned: whether it has been paid and credited, and how many credits it added. This cleanly separates it from create_deposit (which initiates the deposit) and from get_balance, which reports totals rather than the state of one deposit.

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 'Next: once credited, use the account_key with create_inbox or send_message' sentence gives a strong usage anchor: this tool is the gate between paying a deposit and acting on the account. It does not, however, explicitly say to poll repeatedly, what to do if the deposit is still pending, or why one would call get_balance instead.

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