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

Beyond the annotations (readOnlyHint=false, idempotentHint=false), the description discloses a key auth prerequisite ('Needs a DFX account key') and the return shape ('Returns a watch id and checkpoint'). It also explains the `since` behavior of backdating the watch. It does not address non-idempotency or re-call behavior, but it adds genuine behavioral context over the structured fields.

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 action and follows with the scoping, `since`, return, and auth details. It is efficient with no filler, though the run-on enumeration of change types is slightly heavy.

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 complex 11-parameter, nested-object creation tool with no output schema, the description covers the essential context: what is saved, scope options, the backdating `since`, the returned id/checkpoint, and the account-key requirement. It is largely complete, with only minor gaps around re-invocation behavior.

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 all 11 parameters in detail (scope kinds, conditions, baseline, include_failing, etc.). The description reinforces the `since` backdating semantics but adds little beyond what the schema provides, so the baseline of 3 is appropriate.

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 states a specific verb and resource: 'Save a private credit investigation for this account' that tracks 'the changes to watch'. It defines what a watch is and enumerates its scope kinds (borrowers, sponsor, lender book), making the tool's function clear. It does not explicitly name the sibling tools (watch_changes, watch_list) it differs from, keeping it 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?

Usage is implied through the scenarios described (a research question, borrowers, a sponsor's borrowers, a lender's book), so an agent can infer when this applies. However, there is no explicit statement of when to use this versus watch_changes, watch_list, or watch_reevaluate, and no when-not guidance.

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