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

Annotations already declare readOnlyHint=true, and the description reinforces this by mentioning 'no-key access can read it,' implying some tables may not be readable. It also discloses the structure of each returned entry (description, filter column, readability), which goes beyond the bare read-only annotation.

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 is a single, well-structured sentence that front-loads the main action, lists the market-data categories parenthetically, and ends with the crucial 'Call this first' guidance. No wasted words.

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 tool with no output schema, the description fully specifies what an agent will receive: table names with a description, a filter column, and readability status. The 'Call this first' instruction provides contextual placement, making the description sufficient for correct invocation.

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 provides no information to supplement. With a parameter count of 0, the baseline is 4, and the description appropriately focuses on what the tool returns rather than parameter details.

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 states a specific verb and resource ('List every table') and enumerates the exact contents returned: a one-line description, the history-window filter column, and readability under no-key access. This clearly distinguishes it from the sibling describe_table (which presumably details a single table) without needing to name it.

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 explicitly says 'Call this first,' establishing it as the initial discovery step before using siblings like describe_table or run_sql. However, it doesn't explicitly state when not to use it or name alternatives, leaving some inference to the agent.

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