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

The description adds significant context beyond readOnlyHint: true by detailing the full return payload (opcode bytes, category, version, signature, anchors, traps). No contradiction 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?

The description is a single, long sentence that front-loads the action. It is concise but could be slightly restructured for readability (e.g., splitting into two sentences).

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?

With no output schema, the description thoroughly explains return fields, fulfilling the need for the agent to understand what the tool returns. No gaps remain.

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 both parameter descriptions are adequate. The description does not add substantial meaning beyond what the schema already provides, so baseline 3 is 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 description uses specific verbs ('Fetch') and resources ('WebAssembly instruction'), clearly distinguishing the tool from siblings like instruction_list and instruction_search by focusing on a single instruction lookup by mnemonic or opcode.

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 use when a specific mnemonic or opcode is known, but it does not explicitly state when to use this tool over alternatives (e.g., instruction_search for partial matches) nor when not to use it.

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