gryzzly-mcp

update_discount

Idempotent

Change an existing discount's name or amount by identifier; only passed fields are updated and its project or task cannot be moved.

Instructions

Change an existing discount's name or amount, by its identifier. Only the fields you pass are sent. Use create_discount for a new one and delete_discount to remove one; the project or task a discount applies to cannot be moved. Requires Gryzzly's budget offer.

Input Schema

TableJSON Schema

Name	Required	Description
`id`	Yes	The discount's identifier.
`name`	No	A new name.
`amount`	No	A new amount.

Output Schema

TableJSON Schema

Name	Required	Description
`id`	Yes	The discount's identifier.
`name`	No	The discount's name.
`amount`	No	How much is taken off.
`task_id`	No	The task it applies to.
`created_at`	No	When the discount was created.
`project_id`	No	The project it applies to.
`updated_at`	No	When the discount was last updated.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 20, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Annotations already declare idempotentHint=true, destructiveHint=false and readOnlyHint=false, but the description adds behavior beyond them: partial-update semantics ('Only the fields you pass are sent'), an immutability constraint (project/task cannot be moved), and an authorization precondition ('Requires Gryzzly's budget offer'). These are meaningful traits the structured fields do not carry.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with the core action and its identifier scoping, followed by alternatives and constraints. Every sentence earns its place with no filler or repetition of the schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

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 not be described. Combined with the annotations and full schema coverage, the description supplies everything an agent needs: scope, partial-update behavior, immutability limits, sibling routing, and the authorization prerequisite.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the three parameters are already documented, making 3 the baseline. The description adds value beyond the schema by clarifying that unpassed fields are left untouched ('Only the fields you pass are sent'), which explains the nullable/optional semantics of name and amount.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource ('Change an existing discount's name or amount, by its identifier') and immediately distinguishes itself from sibling tools by naming create_discount and delete_discount. An agent can identify the tool's scope without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It names both alternatives explicitly with their selection conditions ('Use create_discount for a new one and delete_discount to remove one'), and adds the constraint that the project/task a discount applies to cannot be moved. Nothing about when to use this vs. siblings is left to inference.

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