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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint. Description confirms these and adds critical behavioral details: on invalid input it returns an error object (never a protocol error), the exact error format, and the retry safety guarantee. This is valuable context beyond the 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 concise with no wasted words. It follows a logical structure: purpose, plan restriction, example, usage guidance, error behavior, and safety note. Each sentence serves a distinct purpose.

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?

For a tool with one parameter and an existing output schema, the description covers purpose, usage context, error handling, content returned, and relationship to siblings. It provides everything an agent needs to select and invoke the tool correctly.

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 has 100% coverage with description 'Product slug exactly as returned by search_catalog.' The description adds a helpful example input ('inbox-zero-assistant') that clarifies the expected format, providing slight extra value beyond the baseline.

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 'loads a product's complete persona definition' with specific verb 'load' and resource 'persona definition'. It distinguishes from sibling tool 'get_full_product' by noting this returns only persona text, not skills.

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 when the caller needs the product's voice and operating rules only.' Provides clear alternative: 'Not when skills are also wanted - get_full_product returns persona and every skill in one call.' Also notes 'PREMIUM (paid plan)' as a prerequisite and explains error recovery.

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