Update Card External Link

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

Annotations already indicate a non-read-only, non-destructive, idempotent mutation, and the description adds meaningful behavioral context beyond them: empty PATCH is rejected before the API call, null clears the label, and a preflight check prevents silent cross-card mutation. No contradictions with annotations.

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 sentences, each carrying a distinct and necessary piece of information, with the core action front-loaded. No filler or redundant restatement of the schema.

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 5-parameter mutation tool with no output schema, the description covers the operation, required inputs, validation precondition, null semantics, and cross-card safety. Nothing essential is missing for an agent 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?

Even though schema coverage is 100%, the description adds critical semantics the schema alone does not convey: neither url nor description is individually required, but at least one must be provided. It also explains that description null clears the label, which is meaningful beyond the raw JSON 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 ('Update') and resource ('url or description of an existing card external link'), making the operation unambiguous. It also clarifies that the link belongs to a specific card, distinguishing it from general card updates and external-link add/remove siblings.

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 actionable guidance: linkId must be discovered via kaiten_list_card_external_links, and at least one of url/description must be provided. It does not explicitly contrast with sibling add/remove tools, but the context is clear enough for an agent to route correctly.

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