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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds genuinely new behavioral facts: the not_found short-circuit that happens before any charge, and the pricing model. It does not cover return shape or how many GPs come back, which is a modest gap rather than a serious one.

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 two sentences are front-loaded and tight, but the pricing is stated twice in near-identical wording ("COST: included in Pro, or €0.10 per call over MPP if you have no key" then "Cost: included in Pro; otherwise EUR 0.10 per call (10 credits) on an agent key, or the same amount paid inline over MPP with no key"). That duplication costs the definition a point on structure.

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 2-parameter read tool with no output schema, the description covers purpose, prerequisites, failure mode, and cost. What its return actually looks like is only implied ("who to approach and what they personally focus on"), which is adequate but not fully closing the gap left by the absent output schema.

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 the fund_slug schema text already says "exactly as returned in the `slug` field of search_funds," so the description's restatement of that requirement adds little. The optional gp_name filter is never mentioned; 3 is the correct baseline when the schema does the work.

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?

"DRILL DOWN to the people: General Partner profiles for a fund you already identified" gives a specific verb (drill down / retrieve profiles), a specific resource (GP profiles), and an explicit scope (a fund already identified). It is cleanly distinguishable from get_fund, which covers the fund itself.

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 description states the selecting condition outright — use it when the question is who to approach and what they personally focus on, rather than what the fund does — which routes the agent away from get_fund. It also states the prerequisite (requires a slug from search_funds) and a when-not case (a fund with no published GP data returns not_found).

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