ism_diff

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

Annotations already provide readOnlyHint=true and openWorldHint=false. Description adds useful context: fails on unknown versions, returns specific structure {from, to, summary, changes}, and change_types behavior (unrequested buckets set to null). Adds value beyond 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?

112 words, front-loaded with main purpose. Every sentence adds value: defaults, alternatives, parameter effects, return structure, failure case. No wasted words.

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 output schema exists, description provides sufficient return structure and error behavior. References sibling tools for context. Covers all necessary aspects without being verbose.

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?

Despite 0% schema description coverage, the description explains all three parameters: from_version and to_version with defaults, change_types with enumerated possibilities and effect (unrequested buckets set to null). This compensates for lack of schema descriptions.

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 it catalogs delta between two ISM versions, using specific verb+resource. It distinguishes from siblings like ism_history (one control's timeline) and ism_versions (loadable versions).

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 explains defaults (version before active vs active), so bare call answers 'what changed in latest release'. Provides alternatives: ism_versions to see loadable versions, ism_history for one control's timeline.

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