ck_set_session

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

Annotations report readOnlyHint=false, indicating mutation. The description confirms this by stating it stores session data for token refresh. It explains the mechanism (cookie storage) without contradicting annotations. It could disclose more about potential side effects (e.g., token refresh behavior) but is sufficient.

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?

Two efficient sentences: first states purpose, second gives actionable instructions. No fluff, front-loaded with key 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?

For a simple authentication setup tool with one required parameter and outputless, the description covers purpose, usage method, and alternative path completely. No gaps remain for an agent to misuse the tool.

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?

Input schema provides a good description for the single 'cookies' parameter. The description adds further context by specifying what the cookie contains (CKAT, CKTRKID, etc.) and how to obtain it, enhancing understanding beyond 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 clearly states the tool's purpose: 'Store a Credit Karma session to enable automatic token refresh.' The verb 'store' and noun 'session' are specific. Sibling tools are transaction/account focused, so this authentication tool is well-distinguished.

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 provides explicit instructions for two usage paths: manually copying the Cookie header or installing the fetchproxy extension. It implicitly tells when to use (when needing automatic token refresh for other Credit Karma tools) but does not explicitly state when not to use or contrast with alternatives.

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