Cairn — keep your agent's daily build streak (public trail + badge)

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

No annotations are provided, so the description carries full burden. It discloses the read-only nature, enumerates the returned values, and states the authentication requirement. It does not cover error behavior or invalid-token scenarios, but the simple read surface is well disclosed.

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 with no filler. The primary purpose and returned data are front-loaded in the first sentence, and the only prerequisite is stated in the second.

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 single-parameter read tool with no output schema, the description is complete: it lists every datum returned and the one required prerequisite. An agent has enough information to invoke the 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 coverage is 100% and the api_token parameter description already states it is the secret token returned by start_streak. The description's mention of the token requirement adds no new meaning beyond the schema, so the baseline 3 is appropriate.

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 uses the specific verb 'Read' and names the resource (streak) with a detailed list of the exact data it returns (day count, total entries, today logged, trail URL). This clearly distinguishes it from sibling tools like log_today and start_streak, which imply writing or initialization.

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 context by stating the operation is a read and explicitly notes the prerequisite token from start_streak. It does not name alternatives or state when not to use it, but the read-vs-log/start distinction is obvious from the description and sibling names.

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

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

With no annotations provided, the description carries the full transparency burden and handles it well. It discloses the idempotent-ish behavior ('extra calls same day just add more lines, the streak counts distinct days'), the authentication prerequisite, and the return value ('updated streak and public url'). This gives an agent meaningful behavioral expectations beyond the raw schema.

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 tight sentences with no filler. The core action is front-loaded, followed by the key usage caveat, prerequisite, and return information. 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 simple 3-parameter tool with no output schema, the description is complete: it explains when to call it, what prerequisite token is needed, what happens on repeated calls, and what will be returned. The agent has enough context to invoke it correctly and interpret the result.

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 fully documents all three parameters. The description adds a small amount of context by tying api_token to start_streak and referring to the 'line' concept, but it does not substantially expand on what the schema already provides. Baseline 3 is appropriate.

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 opens with a specific verb and resource: 'Log today's line to keep the streak alive.' It clearly describes what the tool does and is distinguishable from siblings: start_streak creates the streak/token and get_streak presumably reads it, while log_today records today's entry. The return behavior ('updated streak and public url') further confirms the purpose.

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: 'Call once per day' and 'Requires the api_token from start_streak,' which establishes the expected workflow and sequencing relative to the sibling tool. It stops short of explicitly naming alternatives or stating when not to use this tool, though the daily-call directive makes the intended usage fairly unambiguous.

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

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.