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

With no annotations provided, the description carries the full burden of behavioral disclosure. It usefully explains that the URL is embedded into GPX metadata and that CityHeart never collects donations (donors go directly to third-party platforms). This adds meaningful context beyond the schema, clarifying the tool's side effects and donation flow.

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 concise and well-structured: two sentences, front-loaded with the core purpose, followed by a clarifying note on donation flow. Every sentence earns its place without redundancy or fluff.

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's simplicity (2 parameters, no output schema, no annotations), the description is fairly complete. It explains what the tool does and its behavioral nuance, though it does not explicitly state the return value (a builder URL) or error conditions. Minor gaps exist, but the overall context is adequate for an agent 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?

The schema already covers both parameters with detailed descriptions (100% coverage). The description adds context for fundraising_url by explaining its role in embedding into GPX metadata, but it does not significantly enhance understanding of the city parameter. Baseline 3 is appropriate since the schema does the heavy lifting and the description adds only moderate value.

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 function with a specific action ('Compose a builder URL') and the resource it affects (GPX metadata). It distinguishes itself from siblings by focusing on fundraising links, which is distinct from add_dedication or export_gpx. The purpose is unambiguous and specific.

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 the tool is for embedding a fundraising link into GPX metadata, but it does not explicitly state when to use it versus alternatives like add_dedication or export_gpx. No direct exclusions or alternative suggestions are provided, though the usage context is fairly clear.

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