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

Beyond readOnlyHint=true, it discloses rich behavioral traits: the `days` window is anchored to the latest LOADED settlement date (not today), empty/thin history reflects loaded SEC files rather than absent fails, prices are NOT split-adjusted, an unreachable store REFUSES with DATA_UNAVAILABLE, and data is published twice monthly with ~3-week lag. These are exactly the traps an agent would otherwise misread.

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?

Front-loaded with purpose and return shape before diving into caveats, and every clause carries information (units, anchoring, refusal behavior, cadence). It is dense and long, but little is expendable; a minor trim of redundant window wording could tighten it.

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 specifies the return shape ({ticker, days, history, count, window, coverage, as_of, summary} and per-row fields) and warns how to read `coverage`/`summary` before trusting a gap. Nothing an agent needs to call and interpret it correctly is missing.

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%, so the baseline is 3, but the description adds material meaning: it clarifies the LOADED-settlement-date anchoring of `days` and that `end_date` re-anchors the window elsewhere, which goes beyond the schema's own text. It also pins units (fails in SHARES, price in USD).

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?

States a specific verb+resource ('SEC fails-to-deliver history for one ticker') and immediately frames its analytical role ('the settlement-failure side of short pressure'). It explicitly distinguishes itself from the sibling it complements: 'Pair with ol_short_interest_trend for the other half.' An agent can place it without opening the schema.

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?

Gives clear context (short-pressure analysis, pairing with ol_short_interest_trend) and a concrete usage rule: read `coverage` and `summary` before interpreting a gap, and pass today's date via end_date to measure against the calendar. It stops short of explicit when-not-to-use exclusions, but the routing guidance is strong.

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