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

Goes well beyond the readOnlyHint annotation: it discloses absence semantics (value=null with is_absence=true is a valid answer, explained by metric_availability), confidence gating that EXCLUDES needs_review rows, provenance (issuer's own metric definitions, SEC 10-K/10-Q/8-K/6-K exhibits), and that caveats ride the response's tool_notes. These are non-obvious response behaviors an agent must know.

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-loads purpose, then absence semantics, then filters, then the sibling routing, then source — every clause earns its place. The all-caps emphasis and dense telegraphic packing make it busy but not bloated.

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 carries the return-value burden and does so well: row shape, null/is_absence rows, metric_availability, excluded needs_review rows, and tool_notes caveats. An agent has everything needed to call and interpret this tool correctly.

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 parameters are already documented (the ticker description even explains the deliberate no-cross-issuer constraint). The description restates the optional filters (metric, period, industry) but adds no syntax, format, or interaction detail beyond the schema, so the baseline 3 is appropriate.

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+scope: a 'Tier-3 KPI PANEL for ONE issuer' returning curated per-issuer metric rows. It enumerates the metric family (ARR, RPO/cRPO, NRR, logo retention, DAU/MAU, capacity utilization) and names the sibling it is not, so an agent can distinguish it from ol_operating_kpis without opening either 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 an explicit alternative and the condition that selects it: 'For broad operating KPIs across 26 configured industries use ol_operating_kpis.' It also states the hard usage constraint ('Per-issuer by design') and that no cross-issuer read exists, leaving nothing to inference.

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