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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds valuable context beyond this: it explains the default behavior (latest), the scoping ('engine-wide'), and constraints ('no recommendations, descriptive only'). 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?

Two concise sentences: the first defines the tool's purpose and scope, the second covers the parameter usage. No redundant words or repetition of schema 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?

The tool is simple (one optional parameter) and has an output schema, so return values do not need explanation. The description covers the tool's nature, scope, default behavior, and parameter format—sufficient for an agent to invoke it 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?

The schema provides only the parameter name 'date' with no description. The description compensates fully by explaining the format (YYYY-MM-DD), the default behavior (latest), and that it is optional. This gives the agent everything needed to pass the parameter correctly.

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 identifies the tool as a daily market brief with a specific scope: 'generic engine-wide read' that is 'descriptive only'. It distinguishes itself from siblings by emphasizing it has 'no recommendations', implying a contrast with analysis-focused tools like rayana_ai_analyst_brief.

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?

It clearly indicates when to use the tool ('Latest by default; pass date for a specific day') and implies when not (no recommendations, descriptive only). However, it does not explicitly name an alternative tool, leaving the agent to infer from the sibling list.

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