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

Annotations already cover readOnly/idempotent/non-destructive, but the description adds real behavioral context: limits and allowed values vary per account, so the card must be re-read before each quote, and an unknown or disabled model answers 'model_unknown'. It also delimits what the card will never contain (pricing, routing or billing internals), which tells the agent what not to expect.

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?

Front-loaded with the core action and key source, with no filler sentences. The middle enumeration is dense but each item names a distinct part of the card, so it earns its place; a slightly tighter structure would help.

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?

Covers the full call path (where model_key comes from), the error outcome, and pointers to price/quote tools, while the output schema carries the return shape, so no explanation of returned fields is needed. Only the lang parameter is left entirely unaddressed.

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 description coverage is 0%, so the description must compensate. It does a good job on model_key by pointing to models[].model_key and submodels[].model_key in aimixer_catalog, but the lang parameter (default 'ru', 2-16 chars) is never mentioned anywhere, leaving one of two parameters undocumented in both places.

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 ('read the practical card of ONE exact MixerAI model') and immediately enumerates what the card contains: purpose, input modes with media slots and file limits, prompt length, controls, and choose_when/avoid_when advice. It is clearly distinguishable from aimixer_catalog, aimixer_options, aimixer_estimate, and aimixer_quote, all of which are named.

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?

Explicitly says to read it (or aimixer_options) before each quote rather than relying on remembered model facts, and it names aimixer_catalog as the source of the model_key. It also states the negative boundary: no price, so use aimixer_estimate or aimixer_quote instead.

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