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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it's incremental and ordered 'oldest first,' and it exposes a 'next_since' continuation token, which tells the agent how to page. No rate-limit or freshness caveats, so not a full 5.

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?

Two tight sentences, front-loaded with the core identity and scope, followed by return shape and use case. Every clause carries information; nothing is redundant.

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 no output schema, the description usefully discloses that summaries plus a next_since cursor are returned, which is what an agent needs to chain calls. It's nearly complete for a low-complexity 2-param feed, though it omits any note on ordering guarantees across the cursor boundary or result-count limits beyond the schema's own.

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 already documents both parameters, establishing a baseline of 3. The description reinforces the 'since' semantics ('modified on/after a timestamp,' oldest first) and the continuation flow, but adds no syntax or format details the schema lacks.

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+resource ('Incremental feed of Prozorro.Sale procedures modified on/after a timestamp, oldest first') and labels itself 'the upstream change feed,' which cleanly separates it from the point-in-time siblings prozorro_sale_search/procedure/asset. It stops short of naming those siblings explicitly, so it doesn't reach the full differentiating bar of a 5.

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?

Gives a clear use case: 'track new auctions, status changes and results since a point in time.' That's actionable context for picking this over a static lookup, but it offers no explicit when-not guidance or names the alternative tools to use for one-off or filtered queries.

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