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

Annotations already indicate a read-only, idempotent operation, and the description goes far beyond by detailing the exact response structure (tracked, expired, snapshot_dates), the meaning of gaps, the 60-day TTL bound, and the computation basis for decay. No contradiction with annotations.

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 longer than average but densely organized with clearly labeled sections (Args, RESPONSE, LIMITS). Each sentence adds necessary information, and the structured format makes the complexity manageable without waste.

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 no output schema, the description fully assumes the burden of explaining return values and does so thoroughly: it defines every response subsection, interprets expired opportunities, explains snapshot gaps, and documents history limits. It also accounts for edge cases like TTL and cache-miss behavior, making the tool's behavior predictably 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 coverage is 100%: both days and window already have types, defaults, ranges, and enum values. The description restates defaults and adds the concept of a 'snapshot family', but provides no additional semantic detail beyond what the schema already offers, so the baseline of 3 applies.

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 explicitly states the tool provides edge persistence and decay telemetry from daily snapshots, answering a specific analytical question. It clearly differentiates itself from the sibling 'polymarket_edges' by focusing on time-series persistence rather than current edges.

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 description gives a clear use case: determining how long an edge has existed and whether it is shrinking, with a concrete example contrasting fresh vs. old wide edges. It does not explicitly name alternative tools or exclusion criteria, but the context is sufficient for an agent to select this tool when temporal persistence matters.

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