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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), but the description adds genuine non-annotation context: the required OAuth scope 'favorites:read' and the 'consenting buyer' ownership constraint. That is real behavioral value beyond the structured hints.

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?

Three short, front-loaded fragments: purpose first, then auth scope, then safety. Every clause earns its place with zero redundancy.

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?

With an output schema present, return values need not be described, and the read-only, parameterless nature plus the stated OAuth scope make the definition callable as-is. Only a brief pointer to sibling tools for mutating favorites 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?

The tool takes zero parameters, and the rule sets the baseline at 4 for parameterless tools. There is nothing further for the description to disambiguate.

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?

States a specific verb and resource ('Read ... favorites') and scopes ownership to 'the consenting buyer's existing favorites'. It is clearly distinguishable from add_favorite/remove_favorite by the read semantics, though it never names those siblings explicitly.

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?

'Read ... existing favorites' implies the retrieval use case, and 'Read-only' confirms it is not a mutation. However, there is no explicit when-to-use vs. alternative guidance (e.g. pointing to add_favorite/remove_favorite for changes), so usage is only implied.

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