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

Annotations already mark the tool as read-only and non-destructive. The description adds valuable context by disclosing that it 'looks up EPS, book value per share, and price from SEC EDGAR + market data automatically', which implies external network dependency. No contradiction with 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?

Two sentences with the formula and purpose front-loaded, followed by the alternate input mode. Every sentence earns its place, with no filler or redundant phrasing.

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 no output schema, the description names the key outputs (fair-value ceiling and margin of safety) and both input modes. It does not specify the exact return structure or error behavior, but for a straightforward numeric computation, the named outputs are likely sufficient for an agent to use it correctly.

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 reiterates that eps/bvps/price are used instead of a ticker lookup, which adds a slight clarification about the relationship between parameters, but it does not provide significant new meaning beyond the schema.

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 verb and resource: 'Compute Benjamin Graham's fair-value ceiling ... and the margin of safety against its current price.' The formula is provided, and the description clearly distinguishes between ticker-based lookups and direct parameter inputs, leaving no ambiguity about what the tool does.

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?

Explicitly describes two usage modes: 'just pass a ticker' for US-listed companies, or pass eps/bvps/price directly for a hypothetical company. This is clear when-to-use guidance, and since there are no siblings, exclusions or alternatives are unnecessary.

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