blackboard_exists

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

Declares read-only, no side effects, never modifies state. Describes exact return shapes for success and error, and mentions access checks.

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?

Five focused sentences, front-loaded with action and side effects, no redundancy. Each sentence provides essential information.

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?

With 2 parameters and no output schema, the description fully covers behavior, parameters, return types, and alternatives. No gaps.

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 covers basic descriptions (key, agent_id). Description adds key format example and agent_id usage context, enhancing meaning beyond 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?

Clearly states the tool checks if a key is present and not expired on the shared blackboard. Distinguishes from sibling blackboard_read by noting it's lighter-weight for presence checking.

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?

Explicitly advises to prefer this over blackboard_read when only checking presence, and specifies key namespace format and agent_id scoping.

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