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

There are no annotations, so the description carries the burden of behavioral disclosure. It usefully reveals that the investor count is free while named firms are Pro, which is a significant access limitation. It does not mention authentication, rate limits, read-only behavior, or what happens when no investors are found.

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?

The description is two tight sentences: the first states the core action and direction, the second states the critical free-vs-Pro distinction. Every word earns its place and the most important information is front-loaded.

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 tool with one required parameter and no output schema, the description explains the input, the direction of the query, and the key distinction between count and named firms. It could be more complete with explicit output format or error behavior, but it is largely sufficient for a simple lookup.

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?

Only the optional context parameter has schema-level documentation, while the required slug has none. The description adds meaning by saying the tool operates 'by slug' and that the slug identifies a provider/company. It covers the core required parameter enough to be usable, but offers no format or example details.

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 clearly states the operation: find which VC firms back a given provider/company by slug, and frames it as the 'reverse portfolio' direction. It distinguishes itself from a forward portfolio lookup implicitly, but it does not explicitly name a sibling tool like vc_portfolio, so it stops short of a 5.

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?

The 'reverse portfolio edge' wording gives clear usage context: the agent should use this when starting from a provider/company and needing its investors, rather than starting from a VC firm. It does not explicitly state when not to use it or name alternatives, so it earns a 4 rather than a 5.

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