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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety is covered. The description adds valuable behavioral context: 'reference bands and relative structure only - no exchange quote and no trading recommendation; ELT feedstock absolute prices are deliberately not published; every figure is a range, never a single transactable value.' This informs the agent about the nature of the data returned beyond what annotations state.

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 well-structured with labeled sections (Purpose, Guidelines, Limits, Ex) and is front-loaded with the core purpose. Every sentence adds value: purpose, usage rules, limitations, and examples. It is appropriately detailed for the tool's complexity and does not contain fluff.

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?

The tool has an output schema (as indicated in context signals), so return values need not be explained. The description covers all necessary aspects: what it returns, how to narrow results, which sibling tools to pair with, and critical limitations. Nothing essential for an agent to call it correctly is missing.

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%, so the schema already documents all parameters. The description adds extra semantics by explaining that leaving product/section empty returns the full set, and provides concrete examples (get_price_benchmark(section='rCB'), etc.) that clarify how parameters combine. This goes beyond the schema's per-parameter descriptions, though not drastically.

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 purpose: returning the rCB and virgin carbon black price benchmark structure, detailing the anchor, rCB band, feedstock prices, and more. It clearly distinguishes from siblings by mentioning pairing with get_elt_price_index and get_rcb_index, and explicitly says it provides no exchange quote or trading recommendation, which differentiates it from other price 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 provides explicit usage guidance: 'leave product and section empty for the full set; narrow with section=\'rCB\' / \'feedstock\' / \'international\' / \'cost\'; pair with get_elt_price_index for feedstock indices and get_rcb_index for the layered index series.' It also gives limits (no exchange quote, no trading recommendation) and examples. This is clear when-to-use and when-not-to-use guidance.

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