locker_countFree. Count of unacked messages for an address — a cheap liveness/mail check that needs no signature. Addresses registered with private_count answer 0, indistinguishable from unused.
| Name | Required | Description | Default |
|---|---|---|---|
| address | Yes | EVM wallet address (0x…, the mailbox identity). |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the transparency burden and does well: it discloses that the tool is free, requires no signature, and that private_count-registered addresses are indistinguishable from unused ones. This goes beyond the schema and gives key behavioral context, though it omits details like rate limits or error behavior.
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?
The description is two sentences, front-loaded with 'Free.' and a crisp definition of the tool. It contains no filler and every sentence adds unique value: cost, purpose, auth, and a caveat.
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 simple single-parameter tool, the description covers purpose, cost, authentication, and a behavioral limitation. It does not explicitly describe the return format, but no output schema exists and the semantics are straightforward. The description is complete enough for an agent to decide when to use it.
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?
The schema already provides full coverage of the single parameter (address), but the description adds meaningful behavioral context by noting that addresses registered with private_count return 0. This enriches the parameter semantics beyond the schema's basic type description.
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 clearly states the tool counts unacked messages for an address, with 'a cheap liveness/mail check' as a specific verb+resource. It distinguishes itself from sibling tools by emphasizing it requires no signature and provides only a count, not message content, which separates it from locker_read and locker_send.
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 usage context: a free, unauthenticated liveness/mail check. It includes an important caveat about private_count addresses returning 0, effectively telling users when the result may be misleading. However, it does not explicitly name alternative sibling tools or state 'when not to use' beyond the caveat.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each tool has a clearly distinct purpose: send, read, ack, count, register_key, directory, nonce, capabilities, credit, checkpoint, and status cover different operations without overlap. Even similar-sounding tools like count and read are cleanly separated by scope (message count vs. message content).
All tool names follow a uniform pattern with the 'locker_' prefix and lowercase snake_case. While some postfixes are nouns (capabilities, directory, status) and others verbs (send, read, ack), the style is consistent and predictable, matching the server's domain.
11 tools is well-scoped for a messaging/storage server: each tool earns its place covering setup, messaging, payment, and account management without redundancy or bloat.
The tool surface provides complete lifecycle coverage for the mailbox system: key registration, message sending/reading/acknowledging, directory lookup, nonce generation, payment via credit, persistent checkpoint storage, and status monitoring. No obvious dead ends or missing operations for the stated purpose.