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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds meaningful behavior beyond that: the >50 snapshots sampling-down rule, truncation via max_chars on the first snapshot and max_lines across diffs, and the relative_to diffing semantics. It stops short of describing failure behavior or what the combined output looks like, which keeps it from a 5.

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 framing is front-loaded in the first clause, then parameter mechanics, then the sibling pointer—a logical order with no filler. The middle is dense and semicolon-chained, requiring a careful read, but no sentence is wasted.

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 9-parameter read tool with no output schema, the description covers selection, sampling, truncation, and diff modes well. The main gap is the undocumented 'context' parameter, which an agent would have to guess at; everything else needed to call it correctly is present.

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 coverage is 78%, and the description goes beyond the schema by explaining interplay between from/to/timestamps/sample (evenly spaced, first and last included, capped at 50) and the meaning of both relative_to modes. It does not clarify the unexplained 'context' parameter, which neither schema nor description covers, so not a 5.

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 ('Several snapshots of one monitor in one call') and immediately explains the compact representation: first snapshot in full, the rest as diffs. It also distinguishes itself from the sibling line_timeline for list-content questions, so an agent can differentiate without opening schemas.

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?

It states the exact question this tool answers ('how did this page/its prices change over time?') and names the alternative plus its selection condition: use line_timeline for 'what was added' on a list because it is smaller. Both when-to-use and when-to-prefer-a-sibling are explicit.

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