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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable context beyond these: it explains that the tool never raises protocol errors but returns an error object with fix guidance, that it always returns exactly one skill chosen automatically, and that every call is read-only and idempotent. There is 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 well-structured in three paragraphs: purpose (with example), sibling distinction, and error/behavioral details. Every sentence earns its place. A slight reduction from 5 because the example could be integrated more tersely, but overall concise and front-loaded.

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 presence of an output schema (indicated by context signals), the description does not need to detail return fields. It adequately covers the return shape (slug, skill, instructions), error format, usage boundaries, and safety. For a single-parameter tool with full annotations and an output schema, the description is fully complete.

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% (one parameter with a clear description). The description adds a typical input example but does not provide additional semantic constraints or format details beyond what the schema already includes. Baseline score of 3 is appropriate since the schema does the heavy lifting.

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 verb-resource pairs: 'Load a product's free gateway skill with its complete instructions.' It clearly identifies the tool's unique scope (free gateway skill) and distinguishes it from the sibling get_full_skill by stating 'Not for the product's other skills: those are named and need get_full_skill with a skill_name, which requires a paid plan.' The example further clarifies the return structure.

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 explicitly states when to use ('Use when the caller wants usable instructions immediately.') and when not to use ('Not for the product's other skills'), naming the alternative tool (get_full_skill) and its prerequisites (paid plan). It also explains error handling and retry safety, guiding the agent on correct invocation.

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