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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's job is to add operational detail, which it does: coverage is limited to GB Companies House, no cross-jurisdiction equivalence is inferred, and unsupported calls are rejected before payment. Pricing ($0.0106 USDC via x402 on Base mainnet) is genuinely useful context for an autonomous agent. It stops short of describing result volume or pagination despite a limit parameter.

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?

Four tight sentences, front-loaded with the core capability before scope caveats and pricing. Every sentence carries distinct information (capability, coverage limit, rejection behavior, price). The pricing sentence is arguably secondary but is legitimately decision-relevant.

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?

With an output schema present and rich annotations, the description needn't explain return values, and it correctly focuses on the unusual constraints — jurisdiction coverage and pre-payment rejection. The remaining gap is that it doesn't indicate how many filings are returned by default or how the limit interacts with results, which an agent budgeting calls would want.

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 50%: entity_id is documented in the schema itself, and limit is a self-explanatory bounded integer with a default. The description reinforces that the entity must be 'resolved' but adds no syntax, format, or limit semantics beyond what the schema provides. Baseline 3 is appropriate when the schema carries this much of the burden.

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 states a specific verb and resource: 'Retrieve normalized authoritative filing-history metadata for a resolved legal entity.' The qualifier 'resolved legal entity' plus the coverage scope (GB Companies House) makes the intent clear. It never explicitly contrasts itself with the sibling get_company_filings, so an agent must infer the entity-vs-company distinction from naming alone.

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 rather than stated: 'where supported by its registry' and 'Coverage currently includes GB Companies House filings only' tell the agent when the tool will fail, and 'Unsupported capabilities are rejected before payment' reassures about cost. However, it never says 'use this instead of get_company_filings when...' or specifies prerequisites such as resolving the entity via search_company first — that constraint only appears in the schema.

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