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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds valuable transparency by explaining that prices are refreshed at least twice a day and are 'as of its last refresh, not live at call time,' which is a critical behavioral caveat. It also states what it returns (parts, price, compatibility verdict, FPS, buy link). This goes beyond annotations and adds meaningful context without contradicting them.

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 three sentences long, efficient, and front-loaded with the core purpose. It includes the price-freshness caveat and a clear list of return values. There is no wasted wording, and the structure flows logically from action to constraints to outputs. It is concise without sacrificing necessary details.

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?

Given the tool has three parameters and no output schema, the description adequately explains what the tool returns (every part, price, compatibility verdict, FPS estimates, buy link) and its operational constraints (price freshness, supported countries). It doesn't mention any limitations like whether it returns a single build or multiple options, but that is likely inferred from 'best-value' and the singular 'PC.' Overall, an agent has enough information to invoke it 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?

Schema description coverage is 100% — each parameter (budgetEur, market, compact) already has a clear description in the schema. The tool description does not add parameter-specific semantics beyond what the schema provides, but it does give context that indirectly affects parameter interpretation (e.g., 'best-value' implies budgetEur is used as a hard cap). This is sufficient given the high schema coverage, so a baseline score of 3 is appropriate.

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: assembling a best-value, compatibility-checked desktop PC for a budget. It uses specific verbs ('Assemble') and a specific resource ('desktop PC'), and explicitly distinguishes itself from siblings by mentioning it includes compatibility checks and FPS estimates, which are the concerns of the other tools. An agent can easily identify what this tool does.

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 implies usage (for building a PC from scratch for a budget) but does not explicitly mention the sibling tools or when to use them instead. For example, it doesn't say 'use check_compatibility if you already have parts' or 'use estimate_fps for a quick FPS check.' This is an implicit, not explicit, differentiation, so the guidance is adequate but not strong.

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