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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed world), so the description's job is to add nuance — and it does: the search covers 'the saved (filtered) text' only, and matching is case-insensitive plain text by default unless regex=true or case_sensitive=true. It also discloses that the scan is exhaustive across every snapshot in one call, which hints at cost. It does not discuss truncation behavior when max_lines is hit, which is the main remaining behavioral gap.

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 content density is good and the use cases are front-loaded, but the opening sentence is a fragmented, hard-to-parse clause chain ('...searching every snapshot line by line in one call: every different line that matched with when it was first and last seen, and the periods with a match...'). It rewards re-reading rather than delivering a clean verb-first statement, so structure costs it a point despite little outright filler.

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 eight parameters, no output schema, and a read-only analytical tool, the description does the important work: it describes the shape of the return (distinct lines plus first/last seen and match periods) so an agent knows what comes back. What is missing is the format of from/to (string vs integer timestamps) and what happens when results exceed max_lines, both of which matter for a tool that scans everything.

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 75%, and the description adds real meaning on top: it clarifies the default matching mode (plain text, case insensitive) and the two flags that change it, and it explains group_by=year as counting new matching lines per year rather than just repeating the schema's 'Also count...'. The from/to bounds and max_lines truncation are left entirely to the schema.

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 concrete verb and resource: it searches a monitor's snapshots line by line and returns each distinct matching line with first/last seen times and match periods. That is far more specific than the title alone. It does not, however, explicitly contrast itself with close siblings such as line_timeline, get_changes, or get_history, so an agent must infer the boundary.

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 gives two concrete use cases with an example each: dating a change ('when did the price become 319?') and tracking a topic over time via group_by=year. That is clear context for when to reach for this tool. It stops short of stating when NOT to use it or naming an alternative sibling for overlapping cases.

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