chimera_cache_mark

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

With no annotations provided, the description carries the full burden. It discloses that the tool is lossless, adds cache markers to returned blocks, and returns blocks ready for the SDK system array. It could mention idempotency or side effects, but it is fairly 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 and front-loaded with the primary action. Every sentence adds value—purpose, return format, and benefit—earning its place without verbosity.

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?

Despite having no output schema, the description explains what the tool returns (blocks with cache_control) and the key parameter behavior. It covers the essential use case and benefits, though it could briefly explain the internal caching mechanism.

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 description adds minimal extra meaning beyond the schema (e.g., clarifies that stable=true makes a block eligible for caching). Baseline 3 is appropriate as the schema already documents parameters well.

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: 'Build Anthropic prompt-cache markers for stable text blocks' with a specific verb and resource. It differentiates from siblings by focusing on caching markers for stable text, which is distinct among many chimera tools.

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 implies the tool is for stable text blocks that recur every turn, noting 75-90% token savings. However, it does not explicitly state when not to use it or name alternative tools, leaving usage guidance somewhat implicit.

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