ag_json_diff

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

With no annotations, the description carries full burden, and it delivers: declares determinism, fixture-verified, free for guests with rate limits, API key usage, 500-change cap, and a provenance envelope in the result. It also mandates the payload schema. These are concrete behavioral details beyond what structured fields provide.

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 dense but every sentence earns its place: purpose, use case, behavioral traits, rate limit, api_key, payload schema, and output schema. It is front-loaded with the core function, uses line breaks for readability, and avoids fluff. The inline schemas are compact and necessary.

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?

Given the tool's complexity (diff with constraints, rate limits, provenance), the description covers all necessary context: input requirements (payload schema), output schema (provided), behavioral constraints (500 cap, determinism), and usage context (verifying agent output). Nothing an agent needs 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 0%, but the description compensates fully. It defines the payload's required JSON Schema (a and b objects) and explains the api_key parameter ('pass your Guild api_key to use your member budget'). Without this, the payload object would be opaque. The description adds essential meaning that the schema alone lacks.

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 opens with a precise verb+resource: 'Structural diff of two JSON values with per-path changes.' It clearly states what the tool does (compares two JSON values and returns added/removed/changed paths) and distinguishes it from sibling tools like ag_json_validate or ag_json_repair by focusing on diffing. The use case ('verify an agent's output changed only what it was asked to') further clarifies intent.

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?

Explicitly states when to use: 'Use to verify an agent's output changed only what it was asked to.' It also covers operational context: rate-limited for guests, pass api_key for member budget. While it doesn't list alternative tools, the diff operation is unique among siblings, and the use case is clear enough to route an agent correctly.

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