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

No annotations are supplied, so the description carries the full behavioral burden. It does disclose the meaningful part — the four categories of diff output and the implicit today-vs-yesterday default — but says nothing about whether the date range is bounded, how large a window is permitted, what happens when a snapshot is missing for a date, or the cost/latency of the comparison.

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?

Three tight sentences: purpose first, then the concrete return categories, then the default range. Nothing is padded and the most decision-relevant information is front-loaded.

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 two-optional-parameter read tool with no output schema, the description does the needed extra work by spelling out the four diff buckets an agent will receive. Only edge-case behavior (missing snapshots, date validation, range limits) is absent, which is a minor gap given the tool's simplicity.

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%, and both parameter descriptions already state the YYYY-MM-DD format and the today/yesterday defaults. The description's default sentence merely restates that, adding no new semantics about ordering, inclusivity of endpoints, or whether to_date must be later than from_date.

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 ("Compare two snapshots") and enumerates what the diff contains — regressions, recoveries, new sectors, disappeared sectors — which makes the tool's function concrete. It does not explicitly name a sibling it is distinct from, but the snapshot-comparison purpose is unique among the listed tools (get_sector, verify_snapshot, list_active_signals), so an agent can place it without ambiguity.

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 rather than stated: the description explains the default range (current day vs previous day) but gives no guidance on when to prefer this over, say, verify_snapshot or get_sector, and no when-not conditions. The default-behavior sentence helps an agent call it with zero arguments, but the selection logic is left to inference.

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