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

Annotations already declare readOnly/idempotent/non-destructive/non-open-world, and the description adds substantial context beyond them: pure arithmetic with no I/O or external calls, rounding to 2 decimals, no auth or rate limits, and explicit error behavior (unknown method or missing required parameter returns an error instead of a value).

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?

Dense and front-loaded: purpose first, then usage routing, then the method→parameter mapping, then unit/error conventions. Every sentence carries information, though the packed semicolon-heavy sentences demand careful parsing.

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?

Given 15 parameters, an output schema (so return values needn't be described), and rich annotations, the description covers the essentials: method-dependent parameter selection, input conventions, determinism, and error cases. Completeness is high with only minor room to tighten.

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 already 100%, so the baseline is 3, but the description adds real value beyond the schema by mapping each method to its required parameters (pe_ratio → market_cap + net_income, etc.) and clarifying that only 'method' is required while others are method-dependent. It also documents unit conventions (fractions 0.10=10%).

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+resource ('Market multiples from comparables'), enumerates the exact ratios computed (P/E, P/S, EV/EBITDA, EV/Revenue, regression-adjusted multiple), and names the routing sibling valuation_core. An agent can distinguish this from the other valuation_* tools without opening any schema.

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 states when to use it ('when public comparables exist') and the when-not case with an alternative ('for pre-revenue or private startups use valuation_core'). It doesn't route among the other 13 siblings, but for the primary decision point the guidance is clear.

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