compare_snapshots

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

With no annotations, the description carries the transparency burden. It discloses a crucial limitation (cannot separate market-move contributions) and requires reading the returned 'note' before interpreting numbers as gain/loss. It does not spell out edge-case behavior like missing snapshots or exact response shape, so a 5 is not warranted.

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 sentences with no filler: purpose, output scope, limitation, and a required instruction are all included. The warning is placed at the end but clearly linked to interpretation.

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 tool with no output schema and no annotations, the description conveys the essential return semantics (total and per-holding/per-bucket change) and flags the critical 'note' field. A little more detail about error/edge cases would make it fully complete.

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 both parameters, including the newer default. The description adds the useful semantic 'value change since older' but does not need to restate parameter details.

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-resource pair: 'Diff two stored monthly snapshots,' and names the exact function path portfolio.snapshots.diff_snapshots. It also states the output scope (total and per-holding/per-bucket value change), which distinguishes it from sibling save/list snapshot tools.

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 intended use case is clear: compare two stored monthly snapshots to see value change since an older date. It does not explicitly name alternatives or exclusions, but the sibling set contains only save/list/other analysis tools, so when this tool applies is unambiguous.

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