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

Annotations provide readOnlyHint=true and openWorldHint=false, but the description adds valuable behavior beyond that: deterministic output, byte-identical to meritvalue.com, and returns null when filings don't support a moat or fair value rather than inventing one. This gives the agent a clear model of edge cases and output guarantees.

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?

Three sentences, each earning its place: what it is, key behavioral guarantees (deterministic, byte-identical), and the null edge case. Front-loaded with the core purpose and no redundancy.

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 single-parameter tool with an output schema, the description provides essentical context: the nature of the thesis, deterministic computation, source (SEC filings), and null behavior. It is complete for the intended use.

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 already covers 100% of parameters with a clear description ('Ticker symbol, e.g. AAPL. Case-insensitive.'). The tool description adds nothing specific about the ticker parameter, so baseline 3 is appropriate.

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?

Description clearly states what the tool does: computes an investment thesis from SEC filings, covering business quality and fair value. It distinguishes itself by noting it's deterministic and byte-identical to meritvalue.com, and it's positioned as the first tool to use for 'is it worth owning?' which differentiates it from siblings like get_business_quality and get_intrinsic_value.

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 says 'Use this first when asked whether a company is worth owning,' giving clear context for when to invoke it. It does not explicitly state when not to use it or name alternative tools, but the directive 'first' implies precedence, which is sufficient guidance.

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