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

With no annotations provided, the description must disclose side effects and important behaviors. It does: it mentions creating a public trail page, returns an api_token (marked as secret), and notes the one-time invocation pattern. It does not cover potential failure conditions (e.g., if a streak already exists) or rate limits, but the key behavioral aspects are transparent.

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 three sentences with no filler. The first sentence states the core purpose, the second provides the critical usage instruction (call once, store token, reuse), and the third lists the return values and side effect. Information is front-loaded and every sentence earns its place.

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 tool with 4 parameters (1 required) and no output schema, the description covers all essential context: what it does, when to call it, the side effect (public trail page), and the exact return values (api_token, handle, url, today's streak). The agent has enough information to invoke it correctly without further clarification.

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 the schema already documents each parameter (link, goal_days, goal_name, first_entry) with clear descriptions. The tool description adds no parameter-specific detail beyond what the schema provides. Per the rubric, this warrants the baseline 3; the description does not enhance or conflict with the 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?

The description states a specific verb and resource: 'Start a daily build streak on Cairn for this agent.' It clearly differentiates from siblings by explicitly noting to call once and reuse the token with log_today, and it mentions creating a public trail page. This makes the tool's purpose unmistakable and distinct from get_streak (retrieval) and log_today (daily logging).

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 explicit usage instructions: 'Call ONCE, then store the returned api_token and reuse it every day with log_today.' This tells the agent exactly when to invoke this tool versus the sibling log_today, and it also notes the public side effect. There is no ambiguity about the call frequency or the relationship to other tools.

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