Add or update an intercept-and-transform rule (idempotent upsert)

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

No annotations are provided, so the description carries the burden of behavioral disclosure. It does disclose the key idempotency behavior ('if a rule with the same key exists, its patches are replaced'), which is the critical behavioral trait. However, it doesn't fully disclose what happens with non-key fields, whether partial updates occur, or confirmation/return behavior. Still, the key behavioral aspect is well covered.

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 sentences accomplish everything needed: the primary action with the key structure, the replacement behavior, and when-to-use guidance. Zero waste, front-loaded with the verb and purpose. Efficient and dense.

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 no output schema and no annotations, the description plus the very well-documented schema (100% coverage) gives a complete picture. The patches parameter has rich documentation about __NOW__ macros and dotted-path syntax. The only gap is the lack of return-value/confirmation info, which is common for such tools and not severe given no output schema exists.

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%, so the schema already documents all 4 parameters well. The description adds value by explaining the logical key structure (method + url + regex) that ties the parameters together conceptually, which the schema doesn't convey. The url description in schema already provides substantive guidance about glob/substring matching and short substring advice.

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 function: idempotently upsert a transform rule keyed by (method + url + regex). It explicitly distinguishes this from clear+re-add approaches and names the sibling proxy_mock_transform context. The title adds 'intercept-and-transform rule' clarity. This is specific verb+resource+behavior.

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 explicitly says 'Use this instead of clear+re-add to avoid auto-review friction,' providing direct usage guidance and a rationale. It implies when to use this vs alternatives by highlighting the idempotent upsert benefit over clearing and re-adding rules.

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