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

With no annotations provided, the description carries the full burden. It discloses the exact data the tool returns (first/last session, row counts, symbol count) and frames it as a freshness/coverage check. While it doesn't explicitly state 'read-only', the content and tool name make side effects implausible. It gives useful behavioral context beyond the schema, which has no parameters.

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, each earning its place: the first defines the tool's content, the second states when to call it. No filler, no repetition of the tool name, and the key terms are 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 zero-parameter metadata tool with no output schema, the description covers purpose, content, and usage context. It lists the fields the agent can expect (first/last session, row counts, symbol count) and explains the practical use (freshness). Nothing needed to call the tool correctly 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?

The tool has zero parameters, so the schema is trivially complete. The baseline for 0-parameter tools is 4, and the description offers no confusing or missing parameter information. Nothing more is needed.

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 defines what market_meta does: it returns coverage metadata about the market database, specifically first and last session, row counts, and symbol count. The second sentence explicitly frames this as an action ('Call this to find out how fresh the data is'), distinguishing it from sibling tools that retrieve bars, symbols, or scans.

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 description gives a concrete use case: call this when you need to know how fresh the data is or what the database covers. It doesn't explicitly compare to alternatives like get_bars or search_symbols, but the metadata-focus makes the appropriate context clear. No exclusions are needed given the tool's simple informational role.

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