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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so the safety profile is covered. The description adds genuine behavioral context beyond that: the return payload shape (exact USD decimals, source posts, provider/series identities, fixture labels) and an explicit statement of what the data is NOT (candles, live quotes, exact publication prices). It stops short of describing pagination semantics, which the schema carries instead.

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 sentences, zero waste, and the usage trigger is front-loaded ahead of the return description and the sibling routing. Every clause either tells the agent when to call it or what it gets back.

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 correctly takes on the burden of describing return values, and it does so concretely. Five parameters at 40% schema coverage leave the three required date/asset arguments under-documented, but the capture-time framing and the sibling routing cover the main decision an agent must make.

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 40% – asset_id, date_from and date_to have no schema prose, only patterns. The description partially compensates by framing the range as a 'capture-time window', which clarifies date_from/date_to semantics versus publication time, but it adds nothing about asset_id being a UUID or about the cursor/limit pair beyond what the schema already says.

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 and resource ('inspecting the stored prices captured with posts for an asset') and pins the scope to a capture-time window. It explicitly names the sibling tools it is not (list_market_series/get_market_history), so an agent can route 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 trigger ('Use when inspecting the stored prices captured with posts...') plus an explicit alternative and exclusion set ('Use list_market_series/get_market_history for a price timeline; these captures are not candles, live quotes or exact publication prices'). When-to-use, when-not-to-use and the competing tool are all named.

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