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

Annotations already cover read-only, idempotent, open-world, and non-destructive behavior. The description adds meaningful context beyond annotations: the tool only serves finished sessions, one day per call, and returns a strict subset of get_session. This clarifies data scope and constraints without contradicting annotations.

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?

The description opens with the core definition, then gives crisp usage guidance and exclusions, and ends with limits. Every sentence earns its place, and the structure front-loads the most decision-relevant information.

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 an output schema present, return-value explanation is unnecessary. The description covers what the tool returns, how it relates to siblings, when to use it, when not to, and its hard limits. Nothing an agent needs to select and invoke this 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?

Schema coverage is 100%; the schema already fully documents the 'day' parameter with pattern, examples, and error conditions. The description re-emphasizes 'one day per call' and 'finished sessions only' but adds no new semantic information beyond the schema, so the baseline 3 applies.

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 resource ('dealer-positioning level set for one finished SPX session'), enumerates the exact contents, and explicitly calls itself 'A strict subset of get_session,' distinguishing it from siblings. An agent can immediately tell what this tool returns and how it differs from related tools.

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?

Provides explicit 'Use when' and 'Not for' conditions, naming the exact sibling tools for each excluded case (get_session, get_level_history, get_gex_profile). No ambiguity remains about when to select this tool over alternatives.

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