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

Annotations already cover the safe-read profile (readOnly, idempotent, non-destructive, closed-world), so the description adds real value by disclosing that proxy mode consumes prepaid Aether credits per call and that costs are returned for budgeting. It does not cover pagination or result-shape behavior, but the credit-consumption disclosure is meaningful context beyond the annotations.

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 dense sentences, front-loaded with the core purpose, then mode semantics, then the practical budgeting instruction. No filler; every clause carries information.

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?

An output schema exists, so return-value documentation is not required, yet the description still notes that per-call credit costs are returned. Combined with mode explanations and sibling routing, an agent has everything needed to call this correctly.

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?

With 67% schema coverage, the description compensates by explaining the semantics of the mode values ('indexed' = free partner_search, 'proxy' = proxied calls) and clarifying that ticker filtering spans both indexed docs and proxy endpoints. The limit parameter is left to the schema, but the added meaning is substantive.

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 and resource ('List active marketplace partners (sellers)') and immediately explains the differentiated concept of partner 'modes'. It clearly separates itself from siblings partner_search and partner_proxy_search, which it names and describes.

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 a clear usage condition: call this to obtain per-call credit costs before invoking partner_proxy_search, and explains that indexed mode maps to partner_search. It stops short of explicit when-not-to-use or exclusion criteria, but the routing context is strong.

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