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

Annotations already declare the tool read-only, idempotent, and non-destructive, so the safety profile is well covered. The description adds that the brief is time-bound to 'today' and may be personalised, which is useful context beyond the annotations. However, it does not clarify what 'personalised when available' means or how output may vary, so it adds moderate but not extensive behavioral insight.

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 a single sentence with the core resource, 'Today's market brief,' placed up front. The 'what matters now' pulse phrase is somewhat vague but brief, and the personalization caveat adds useful information. It is efficient, though not maximally precise.

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 zero-parameter, read-only tool with an output schema, the description is mostly sufficient. The main gap is the lack of differentiation from similarly named sibling briefs, which could lead an agent to select the wrong tool. The vague personalization note also leaves some ambiguity about what the returned brief will contain.

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 accepts zero parameters and schema description coverage is effectively 100%, so there is no parameter meaning for the description to clarify. The baseline of 4 applies because no parameter documentation burden exists. An output schema is also present, so return-value structure is handled outside the description.

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 resource: a brief focused on today's market, described as the 'what matters now' pulse. It is reasonably distinct from data-oriented tools like get_market_data and from briefs with a different scope like get_executive_brief or get_country_brief. However, it does not differentiate itself from the similarly named get_today_brief, so it falls short of a 5.

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 provides no explicit when-to-use guidance and names no alternatives. With siblings like get_today_brief, get_executive_brief, and get_country_brief, an agent cannot determine when this brief should be preferred. The 'personalised when available' note is a behavioral hint, not a selection criterion.

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