Market snapshot

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

With no annotations provided, the description carries the full behavioral burden and does well: it discloses that field ages are stated, unreadable fields return null and are listed in 'missing', and nulls are never replaced with zeros. It does not explicitly say the operation is read-only or mention authentication or rate limits, but 'snapshot' and the absence of mutation signals make the safety profile reasonably clear.

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, no filler. The first sentence front-loads the purpose and scope, the second adds a crucial data-quality caveat about null handling. Every clause earns its place.

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 simple two-parameter snapshot tool with no output schema, the description covers the important output behaviors: what market facts are included, that ages are stated, and how missing fields are represented. It does not describe exact response formatting, but the core information an agent needs to select and interpret the call is present.

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 100%, so the baseline is 3. The description does not add parameter-level meaning beyond the schema, but the schema already fully documents symbol and depthLimit with constraints and examples, so the agent is not left guessing.

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?

The description clearly identifies the tool as a market snapshot and enumerates specific contents: top of book, spread, 24h range, book depth, and lot/notional filters. It lacks a single strong verb like 'retrieves' or 'gets', but 'The market facts a trading decision rests on' combined with the tool name makes the purpose clear and implicitly distinguishes it from the preflight siblings.

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?

The phrasing 'a trading decision rests on' implies this is the tool to consult for current market conditions before trading, but it does not explicitly state when to prefer it over preflight_trade or preflight_rules, nor does it mention any exclusions. Usage context is present but not directly actionable.

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