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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely useful beyond-schema context: pricing model, ~96% signal coverage, and that not_found is returned before payment so a bad slug is never charged. This is above the annotation baseline but the cost is stated twice, diluting the 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?

The opening sentence is well front-loaded and the coverage/not_found detail is valuable. However the cost is stated twice in near-identical form ('COST: included in Pro, or €0.10 per call over MPP if you have no key' and the trailing 'Cost: included in Pro; otherwise EUR 0.10 per call...'), so one full sentence does not earn its place.

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?

No output schema exists, so the description must describe returns, and it does so concretely (thesis, signals, dos/don'ts, deployment status, source URLs). Pricing, failure behavior and preconditions are all present — nothing an agent needs to call correctly is missing.

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% and there is only one parameter, so the schema already documents the slug format and its provenance. The description restates the 'call search_funds first' guidance, adding no new syntax or format detail beyond what the schema says.

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 (drill down) and resource (investor signals for a fund), and enumerates the payload: GP thesis, bullish/contrarian signals, founder dos and don'ts, deployment status, source URLs. It also distinguishes itself from search_funds and get_fund, which are named directly.

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?

Explicit sequencing guidance: use after search_funds/get_fund, before writing outreach to a specific fund. The slug parameter description reinforces the dependency ('Call search_funds first rather than guessing').

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