Record a fact about a company

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

Annotations confirm this is a non-destructive write (readOnlyHint=false), and the description adds genuinely useful behavior: only sourced facts reach a brief, sources are validated against prior research_company reads, and PII is prohibited. It doesn't say what happens when the source check fails or whether duplicate facts are merged, which keeps it from a 5.

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?

Four short sentences with no filler; the core action, the sourcing rule, and the PII constraint are all front-loaded. Every sentence carries a distinct constraint.

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 4-parameter mutation tool with no output schema and full schema coverage, the description covers the essential constraints an agent needs to call it correctly. It omits only return behavior and what happens on rejection, which are minor given the tight scope.

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 100%, so the baseline is 3, but the description adds real meaning beyond the schema: the sourceUrl must be a page previously read by research_company for that company, and 'inference' is defined semantically rather than just enumerated. The statement field's non-PII constraint is also clarified.

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?

Opens with a specific verb+resource ('Records one fact about the company') and immediately scopes it with the required provenance ('with the page it came from'). This clearly separates add_fact from read-only siblings like get_company_context or research_company.

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?

Gives concrete conditions: the source must be a page research_company read for this company, and 'inference' is reserved for conclusions rather than reads. It stops short of naming an alternative tool for facts that lack a source, but the when-to-use constraint is explicit enough to route correctly.

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