explain_diff

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses that output is 'in plain English' and that it analyzes the 'current state of a session,' suggesting a read-only operation, but it does not explicitly state side effects, permissions, or limitations. This is adequate but lacks explicit clarity on whether any modification occurs.

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 two sentences, front-loaded with the primary action, and every sentence adds value. The first sentence defines the operation, and the second explains the use case, with no redundant or filler content.

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 simplicity (2 parameters, no output schema, no annotations), the description covers the core elements: what it does, when to use it, and the nature of its output. It does not specify return details or error scenarios, but these are less critical for an explanation tool. The description is sufficiently complete for the context.

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?

The input schema has 100% coverage with descriptions for both parameters (session_id and target_version_id). The description adds context by framing the comparison as 'current state' versus 'target version,' but this does not introduce new semantics beyond what the schema already provides. Baseline of 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 clearly states the tool's function: explaining differences between a session's current state and a target version in plain English. It uses a specific verb ('explain') and resource ('session', 'target version'), and it distinguishes itself from siblings like compare_versions by emphasizing the plain-English output rather than raw diff.

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 clear context by stating it is 'useful for understanding what changed without parsing raw diff output,' which implies the tool is for high-level analysis. However, it does not explicitly name alternative tools (e.g., compare_versions) or state when not to use it, so it falls short of full exclusionary guidance.

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