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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond the annotations: it explains the subtle distinction that an exposure's first assessment is a transition but not a status change, and it details what the transitions_since mode returns (causes, citation ids, register record). This is meaningful behavioral disclosure that helps the agent interpret results correctly.

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 dense paragraph that front-loads the core purpose and then expands into the optional mode. It is longer than ideal but every clause adds information: the status bands, the transition/change distinction, the overdue review count, and the transitions_since behavior. The final sentence acts as a usage guide. It could be split into two sentences for readability, but it is not bloated.

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 read-only tool with one optional parameter and no output schema, the description covers the key information an agent needs: what the tool returns, the meaning of the optional parameter, and the semantic distinction between transitions and changes. It does not describe the exact response shape, but with no output schema and a read-only annotation, the description carries the burden well. A perfect score would require explicit mention of pagination or response format, but those are minor gaps.

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 description coverage is 100%, so the schema already documents the transitions_since parameter. The description adds value by explaining what the parameter triggers (listing individual transitions with causes) and the ordering ('newest first'), which goes beyond the schema's basic description. The baseline is 3 for full coverage, and the description earns a 4 by adding behavioral meaning to the parameter.

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 opens with a specific verb and resource ('Current health of the monitored portfolio') and enumerates the exact metrics returned: status bands, active exposure count, transitions, status changes, overdue reviews. It also distinguishes the optional transitions_since mode, which lists individual transitions with causes. This clearly differentiates it from siblings like portfolio_book and company_events.

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 says 'Start here for questions like how the book is doing or what changed since a date and why.' This gives the agent a clear trigger condition and implies it is the first tool to try for portfolio health questions. It also explains when to use the optional parameter, making the usage context unambiguous.

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