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

Annotations already declare write/non-destructive/closed-world; the description adds real behavioral context beyond that by disclosing that a snapshot of deadline, subsidy cap, rate, and target region is captured at registration time to detect later changes. It omits error behavior for invalid subsidy_id and any auth notes.

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?

Front-loaded with the core action and the upsert caveat, which is good. But the full status enum listing duplicates the schema's enum verbatim and consumes roughly a third of the text without adding information for the agent.

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?

An output schema exists, so return values need no explanation, and for a 3-parameter upsert the definition covers the main behavior (create-or-update, snapshotting for change detection). Gaps are minor: no failure modes, no note constraints, no guidance on obtaining a valid subsidy_id.

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 0%, so the description must carry the burden. It clarifies that status is a workflow state and that note is a memo field updated on re-registration, but it mostly restates the enum values already in the schema and says nothing about note format/limits or what subsidy_id should reference.

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 (register a subsidy in the watchlist) and adds the crucial upsert nuance: if already registered, status and note are updated. That distinguishes it from list_watchlist and unwatch_subsidy by implication, though no sibling is named explicitly.

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 upsert clause tells the agent this tool also serves as the update path, which is useful implied guidance. However, there is no explicit 'use this when…' / 'use X instead' routing, and no prerequisites (e.g., subsidy must exist, must be obtained via search_subsidies first).

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