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

With no annotations, the description carries the full load and does well: it names the geocoding dependency (postcodes.io), the 24h cache, the data license (© OpenStreetMap contributors / ODbL), and that outbound soft-offers are disabled. It omits failure behavior for invalid or non-UK postcodes and does not say whether results include distance or category fields.

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 short clauses, front-loaded with the scope ('Free peek: up to 5 …'), then supporting facts about geocoding, caching, licensing and the disabled upsell. Nothing is padded; every fragment carries distinct information.

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 simple two-parameter read with no output schema, the description still leaves the return shape unspecified — an agent does not know which amenity fields come back (name, type, distance) or how errors surface for a malformed postcode. Adequate but with a real gap given the absence of an output schema.

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 coverage is 100%, so both parameters are already documented. The description only restates the postcode format and the 5-result cap, adding no new semantics such as what 'size' below 5 does or whether outcode results differ from full postcode results. 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?

States a concrete resource and scope: nearby OSM amenities for a UK postcode/outcode, capped at 5 for the free tier. The 'Free peek' framing hints at the paid sibling local_amenities_pack, but it never names it, so an agent must infer the tier relationship.

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 word 'Free peek' plus 'max 5 for free' implies this is the trial-tier lookup and that a fuller pack exists, but no explicit when-to-use or when-to-switch guidance is given relative to local_amenities_pack or local_context_pack. Usage is implied rather than stated.

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