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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, yet the description still adds real value: a ~60-second shared snapshot, nothing is held or reserved, the reserve step rechecks, and missing types are not treated as zero. These are exactly the freshness and negative-result caveats an agent cannot get from the annotations, though the feed's source and failure modes are not described.

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 definition is front-loaded with a read-only marker and then packs distinct facts into five short clauses with no filler. The only redundancy is the explicit 'Read-only:' prefix, which annotations already convey.

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?

This is a single optional-parameter read tool with an output schema, so return values need not be explained. The description covers freshness, non-reservation, and the 'missing is not zero' pitfall, which is everything an agent needs to interpret the result 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?

Schema coverage is 100% with a fully documented single parameter, and the description still goes beyond it by explaining that a value may match either the live feed or a published size, and that a published size missing from the feed is not listed as open. That disambiguates the filter's behavior rather than restating the schema.

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 specific verb and resource: reads the SJ Storage public availability feed and returns unit types, sizes, monthly rent, deposits and open counts. The scope is concrete, but it never distinguishes itself from the close sibling get_units_and_prices, leaving the agent to infer which to call for pricing versus availability.

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 through the filter semantics ('Optional unit type or size matches the current feed or the published sizes') and the schema note to omit the argument to list all types. There is no explicit when-to-use or when-not-to-use statement and no reference to the sibling tools that overlap with this one.

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