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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so the safety profile is covered. The description adds real context beyond that: the data provenance (enrichment graph), the fact that it is a paid pay-as-you-go credit operation requiring an API key, and the mapping to a specific REST endpoint. It stops short of covering empty-result or rate-limit behavior, so not 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?

Three short sentences, front-loaded with the capability and the returned fields before the endpoint equivalence and cost note. No filler, though the REST endpoint reference is only useful to a subset of callers.

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 correctly compensates by enumerating the return payload (total raised, rounds, latest round, investors, dates) and covers the auth/credit requirement. For a one-parameter read tool that is close to sufficient; the missing piece is disambiguation from sibling funding tools.

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?

There is a single parameter at 100% schema description coverage with an example ('anthropic.com'), so the schema carries the semantics. The description only echoes 'by domain' and adds no format, normalization, or failure behavior for invalid domains — baseline 3 for a fully documented single param.

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 names a specific resource (company funding) and keying dimension (domain), and enumerates the returned fields — total raised, rounds, latest round, investors, dates. It is clear what the tool retrieves, but it never distinguishes itself from close siblings like get_startup_funding_history or query_funding, leaving the agent to guess which funding endpoint applies.

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?

Usage is only implied: you need a domain and a funded API key with credit — a genuine prerequisite that is stated explicitly. However, there is no statement of when to prefer this over query_funding, get_startup_funding_history, or enrich_company, which is exactly the ambiguity an agent faces in this crowded funding/investor cluster.

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