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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), and the description still adds substantial behavior: which engine produced the result is surfaced via `engine`, a slow `monolith_rescue` fallback may re-run a module and is billed, a 10-minute client timeout is advised, and only double failure yields status FAILED. That is exactly the context annotations cannot convey.

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 payload is front-loaded: purpose and returned fields come first, operational caveats after. It is dense but each clause carries decision-relevant information (timeout, billing, failure mode); the Fast Extraction internals (page scout, deterministic readers) are the one stretch an agent does not strictly need.

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?

An output schema exists, so return values need no explanation; the description instead covers the operational envelope — engine routing, rescue latency, timeout guidance, failure semantics — which is precisely what an agent needs to invoke this correctly and to avoid premature timeouts.

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% and both parameters carry meaningful descriptions (including the https-only vs stdio path distinction), so the schema does the heavy lifting. The description adds no parameter-level detail of its own, making the baseline 3 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 first sentence gives a specific verb plus resource (extract the register map) and enumerates the exact contents returned: memory addresses, reset values, RO/RW/W1C access permissions, and per-bit field definitions. That enumeration distinguishes it from adjacent extract_* siblings such as extract_peripheral_matrix or extract_pinout, so an agent can choose without opening the schema.

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 explains the execution model (Fast Extraction, fallback to deep engine) but never states when to reach for this tool versus sibling extractors, nor any prerequisites beyond the schema's URL note. Usage is implied by the content enumeration rather than stated as an explicit selection rule.

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