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

Annotations already indicate readOnlyHint=true, establishing the tool is safe. The description adds useful context about API key requirements and 403 semantics, which goes beyond the structured annotations. This extra behavioral detail helps the agent handle errors correctly.

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 two sentences long, with the core purpose front-loaded in the first sentence and an important error-handling caveat in the second. Every word contributes value; there is no fluff or repetition.

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 tool with 0 required parameters, an output schema, and rich schema descriptions, the description is sufficient. It covers the core action and the non-obvious auth caveat. It does not explain return formatting, but the output schema covers that. Slightly missing is an explicit mention of ranking direction (e.g., undervalued ascending), but 'Rank... by value' implies it.

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 input schema fully describes both parameters (limit and model) with 100% coverage, including enum values for model. The description merely references 'a chosen model's value' without adding new meaning to individual parameters. Baseline 3 is appropriate since the schema carries the explanatory load.

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 states the tool ranks covered companies by a chosen model's value, using a specific verb ('rank') and resource ('covered companies'). This distinguishes it from sibling tools that fetch data for individual companies (e.g., get_intrinsic_value, get_fundamentals). The purpose is unmistakable.

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 implies use for screening across the covered universe, contrasting with sibling tools focused on single-company details. It also provides practical guidance: a 403 indicates a plan limitation, not a retryable error. However, it does not explicitly state 'use this when you want a broad screen, not when you need a single company's data,' leaving room for ambiguity.

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