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

Annotations already establish this is a non-destructive write (readOnlyHint=false, destructiveHint=false). The description adds two meaningful traits beyond them: patch semantics (only sent fields change) and the return behavior ('returns the value as it now stands'). It omits permissions or idempotency details, keeping it from a 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?

Front-loaded verb+resource followed by the essential qualifier, then read-first advice and return behavior. Three tight clauses with no filler, though the ordering could put the read-first prerequisite even earlier.

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 13-parameter mutation tool with no output schema, the description covers the critical gaps: patch semantics, a read-before-write workflow, and return behavior. It lacks error/idempotency notes but is otherwise sufficient for correct invocation.

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 77%, so the schema descriptions largely carry the parameter burden (id sourcing, amount units, period semantics). The description adds no syntax or format detail beyond the schema, so the baseline of 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?

The verb+resource is specific ('Change a direct fee row') and it clarifies the partial-update scope ('only the fields sent change'), which separates it from wholesale replacements. It does not explicitly name the sibling alternatives (add_fee, delete_fee, update_price), so it stops short 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?

It gives a real prerequisite workflow ('read the current value with its read tool first'), which is genuine usage guidance. However, it never states when to choose update_fee over siblings like update_price or delete_fee, so the routing condition is only implied.

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