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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world), so the description's incremental value is the data cadence ('end-of-day') and the payload contents (level, recent returns, strongest/weakest sub-indices). That meaningfully helps an agent know what it will get and how fresh the data is.

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?

A single sentence with the resource, the enumeration, the freshness qualifier and the return contents — no filler, and the core purpose is front-loaded.

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 one-required-param lookup with no output schema, the description supplies both the return shape and the end-of-day cadence, so nothing an agent needs to call or interpret the tool 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 baseline is 3, but the description goes further by defining each enum value (RUBIN = AI buildout, HALO = non-AI growth, AW40 = AI deployment, AEI = agentic stack, EUROAI), which the schema only labels generically as 'Index code'.

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 ('Current snapshot of one proprietary Closelooknet index') and enumerates the five index codes with short glosses. The word 'one' implicitly separates it from the multi-index sibling compare_indices.

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?

Usage is implied by 'one ... index' — an agent can infer this is the single-index lookup and compare_indices is the multi-index one — but there is no explicit when-to-use or when-not statement and no alternative is named.

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