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

The annotations already declare readOnly, idempotent, closed-world, and non-destructive behavior, so the safety profile needs no extra words. The description adds genuinely useful context beyond them: the data vintage (2026) and the coverage scope (392 cities nationwide), which tells an agent how fresh and how broad the dataset is. It does not address what happens for an unsupported or ambiguous city, which keeps it from a 5.

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?

Two compact sentences with no filler. The resource and the returned fields are front-loaded, and the coverage claim is a short, useful trailing clause.

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 values need no explanation, and the sole parameter is fully documented in the schema. What is missing is edge-case behavior, such as unknown city handling or whether 2026 figures are provisional, which matters for a data-lookup tool that claims exactly 392 cities.

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%: the single city parameter already documents accepted formats (Chinese name, pinyin slug, or 6-digit administrative code) with examples. The description adds nothing about the parameter beyond what the schema provides, so the baseline 3 applies.

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 names a specific verb and resource: it retrieves the 2026 base limits, the contribution rates for each insurance type (individual and employer), and the official verification basis for a given city. It is clearly distinguishable from the calculate_* siblings and implicitly from query_social_security_policy. However, it never explicitly names the sibling it differs from, so it falls short of a 5.

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?

Usage is implied: call this tool when you need numeric contribution limits or rates for a city, rather than when you need a tax or pension calculation. There is no explicit when-not guidance, no prerequisites, and no mention of query_social_security_policy as the alternative for policy narrative versus numeric data.

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