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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description goes further by disclosing the data provenance (SEC 10-Q filings, as-of date), the free-vs-paid split, and the auth requirement for full access, which is meaningful context beyond the 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 core purpose is front-loaded in the first clause, which is good. However, the payload is delivered as one dense run-on sentence followed by a statistics sentence (20.4% vs 2.8% next-quarter cuts) that is persuasive framing rather than information an agent needs to invoke the tool correctly.

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 no output schema, the description must carry the return-value burden, and it does reasonably well by listing the free fields and the full-tier fields. Combined with the disclosed source, as-of date and auth requirement, an agent has enough to call this correctly, with only minor looseness about exact response shape.

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 both the name and full parameters are already documented in structured form, setting the baseline at 3. The description does add some value by enumerating exactly what full=true returns (every fund's mark, par, prior-quarter mark, filing link), but it largely restates the schema's own note about the Tensorust key.

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 names a specific resource (private credit marks / BDC fair values as a share of par for a named US borrower) and specifies the underlying source (10-Q filings for 2026-06-30). An agent can tell this is a per-company lender-mark lookup rather than a portfolio aggregate like credit_q3_cuts or credit_disagreements, though those siblings are never named 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?

Usage guidance exists only at the tier level: it explains what the free call returns (lowest/highest manager mark, gap, three funds) versus what requires full=true and a Tensorust key. There is no guidance on when to pick this over the nearby credit_disagreements or credit_q3_cuts tools, so tool selection is left to inference from the sibling names.

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