Citybook

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

Annotations already declare read-only, idempotent, non-destructive behavior, so the description only needs to add context. It adds the important x402 payment requirement for credential-free calls, notes that no Citybook key is needed, and previews the rich output fields. The sentence about 'Connect and list the paid event tool' is a bit confusing, but not contradictory.

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 mostly compact and front-loaded with the core purpose, but the sentence 'Connect and list the paid event tool without a Citybook key' is awkwardly worded and unclear. The remaining sentences are useful, but this ambiguity lowers the structure quality.

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?

For a read-only search tool with 12 well-documented parameters and no output schema, the description covers the essential scope, filter possibilities, return metadata, and payment/authentication context. Minor omissions like pagination behavior and exact result shape are acceptable because the schema covers parameters and annotations cover safety.

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%, so the schema fully documents all 12 parameters. The description only summarizes filter categories (city, neighbourhood, sector, date range, accessibility flags) without adding syntax, defaults, or relationships beyond what the schema already states; 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 concrete resource ('upcoming local events') and a specific action ('Find'), backed by examples of event types and filter dimensions. Even without siblings, an agent can tell this is a search/fetch operation for event data, not an administrative or write tool.

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 clear context: it is the event-search path for local filters and provides guidance on authentication ('credential-free fetch_events calls require x402 payment; other tools require Bearer authentication'). It does not name alternatives or state explicit when-not conditions, but with no sibling tools listed, the context is sufficient.

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