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

Adds meaningful behavioral context beyond annotations: it is free, requires no payment (no x402 challenge), and returns no change events. It also provides the toll quote and HTTP endpoint. While it doesn't cover rate limits or authentication, the annotations already cover safety and idempotency.

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 main purpose and reasonably concise. The toll quote and HTTP equivalent are useful but could be trimmed. Every sentence contributes to understanding, with no wasted text.

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 purpose, inputs (partially), payment, and output nature (no change events). However, for a tool with 0% parameter description coverage and no output schema, it should clarify what the pre-check returns (e.g., validation results, identity resolution output) and specify the semantics of each input parameter.

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 has 4 parameters with 0% description coverage. The description only mentions 'an identity and/or {since}' and the feed-wide behavior when only {since} is given, but it never explains the individual parameters (inn, name, ema_product_number) or how they form an identity. This leaves significant ambiguity for an agent.

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 ('pre-check twin') and resource ('ema_changes'), lists the operations it performs (validation + identity resolution + coverage + toll fingerprint), and explicitly says it produces 'no change events,' which clearly distinguishes it from the sibling ema_changes.

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?

Identifies itself as a FREE pre-check twin for ema_changes, implying it should be used before the paid version. States 'no payment required' and that you only pay for delivered answers (in ema_changes). It doesn't explicitly say 'use this when you don't need actual change events,' but the context is clear enough.

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