Writes text to a slot that outlives the call. slot and value required; 32 KB a slot, 64 slots, 256 KB in total. public true makes the slot readable at https://gregbenza.ai/locker//. Send ticket, or name and key; a call with neither returns a new ticket to send next time.
| Name | Required | Description | Default |
|---|---|---|---|
| key | No | ||
| name | No | ||
| slot | Yes | ||
| value | Yes | ||
| public | No | ||
| ticket | No | a ticket from an earlier write; send this instead of name and key |
Changes observed during successful MCP inspections.
Input schema / properties / ticketAdded value: +{
+ "description": "a ticket from an earlier write; send this instead of name and key",
+ "type": "string"
+}Input schema / requiredPrevious value: -[
- "name",
- "key",
- "slot",
- "value"
-]New value: +[
+ "slot",
+ "value"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description carries full behavioral weight. It adds significant transparency: persistence across calls, total capacity (32 KB/slot, 64 slots, 256 KB total), the public-read behavior via URL, and the 'no credentials → returns new ticket' side effect. This goes well beyond the minimal write semantics.
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 concise sentences: first states purpose, second covers capacity, third covers auth and public visibility. Each sentence earns its place without redundancy or verbose explanations, and the most critical information is front loaded.
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?
Given six parameters, no annotations, and no output schema, the description does a near-complete job. It defines all parameters, supplies limits, auth, and visibility rules. It does not describe the success response or overwrite behavior, but that is marginal for choosing and invoking this write tool correctly.
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 only 17% (only 'ticket' has a schema description), so the description must compensate. It clarifies slot (size/limits), value (text content), public (readable URL), and the name/key/ticket auth triplet. Every parameter receives meaningful extra explanation beyond the raw type.
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 action: 'Writes text to a slot that outlives the call.' This is specific (slot resource) and differentiates from sibling reads like locker_get and locker_index via the verb 'writes' and lifespan emphasis.
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 concrete invocation guidance: required 'slot' and 'value', size limits, optional 'public' with a canonical URL, and an explicit auth flow (send ticket or name/key, with a new ticket to send next time if neither is provided). It does not explicitly compare with siblings like deaddrop_leave, but context is clear enough for selecting write vs read tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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