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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds two genuinely useful behavioral facts: the odds data comes from local snapshots (implying possible staleness/provenance constraints) and the output is research material, not signals. It still omits freshness cadence, snapshot coverage/coverage gaps, rate limits, and the response shape, so the value added above the annotations is modest.

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?

Two short sentences with no filler, and the data-source inventory is front-loaded. However, the telegraphic, verbless construction and the separated 'Research only' disclaimer read as fragments rather than a structured, self-explanatory statement of what the call returns.

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?

There is no output schema, so the description must carry the full burden of explaining the return value, and it does not — an agent cannot tell whether FNG and odds are returned as two series, how they are keyed, or what units/fields appear. Combined with an undocumented required parameter and no pricing detail beyond the title's $0.01, this is under-specified for a multi-source data tool.

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 description coverage is only 33%: api_key is documented in-schema, but the required market parameter and the days parameter have no descriptions anywhere. The description does not compensate at all — it never says whether market takes a Polymarket slug, a Manifold ID, or a free-form query, nor whether days accepts arbitrary ranges or caps out at the 7 in the title.

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?

"Local Polymarket/Manifold snapshots + Alternative.me daily FNG" names the data sources the tool returns, which is more specific than the bare name, but it is a telegraphed fragment with no verb and never says what is actually produced (a per-market time series?) or over what window. Only the title's "7-day history" supplies that scope, so an agent must stitch purpose together from name, title, and description.

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?

"Research only — not trade signals" is a caveat about interpretation, not a routing rule, and there is no explicit when-to-use or when-not-to-use guidance relative to siblings like odds_pulse, odds_movers, odds_hypothesis, or free_odds_sample. Usage is only implied by the word "history" and the data-source list.

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