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

There are no annotations, so the description must carry the burden. It does convey that this is an official-API, read-style tariff lookup and even discloses the monetary cost. It still doesn't clarify whether authentication is needed, what format the response takes, or whether any side effects exist. A small gap, but not a major hide of behavior.

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 one line and immediately specifies the domain ('Post Russia'), the purpose ('cost and delivery time'), the scope ('between inde'), and even cardinality. Every sentence earns 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?

The tool has no. output schema, no parameter descriptions, and no annotations. The description only provides the semantic purpose. An agent would not know how to map a source/destination pair into the wrapper schema, nor what to expect in the response. This is slightly too sparse to be considered complete.

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?

The schema offers no descriptive coverage (0%) and the description only implies 'between indices' — meaning the tool needs at least two postal indexes. It does not specify how to pass them under the required 'args' object, or explain 'extra'. The agent cannot reliably determine parameter names or value formats from the description alone.

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 tool's purpose: providing Russian Post shipping costs and delivery times between postal indices, using the official API. The $0.01 USDC pricing also tells the agent this is a paid, likely fast operation. This distinguishes it from siblings like pochta_track or pochta_address.

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 gives a clear-use context: 'cost and delivery time between indices.' However, it does not mention when not to use it or compare it with related siblings such as pochta_delivery_time, which appears to handle delivery times alone. The intended usage is implied but not explicitly differentiated.

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