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

Annotations already declare read-only, idempotent, non-destructive, closed-world behaviour. The description adds value beyond that: 'newest first' ordering, the legacy-client fallback that additionally returns savedLibraries.giphy and savedLibraries.stock with availability and individual limits, and what fields come back for GIPHY items.

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-loads the default case before the source-specific branches, and every sentence carries information. The GIPHY clause is tangled prose ('each with its name... and tags..., which say what it shows, and editorLink for ignix-editor giphy') and could be tightened, but nothing is filler.

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 carries the return-value burden and mostly does: it covers ordering, GIPHY item fields, and the legacy savedLibraries payload. It does not describe the fields of default image/video items, which leaves a small gap for the primary case.

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 75% and the description meaningfully extends it: it defines what source=giphy and source=stock actually return, what name and tags mean ('GIPHY's own... say what it shows'), and what editorLink is for. It leaves type and limit to the schema, which is reasonable given they are already documented.

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 ('Images and videos already generated or uploaded by this organization') and enumerates the three retrieval modes (default, source=giphy, source=stock) with their distinct scopes. The org-owned saved-library scope is clearly separable from siblings like list_account_media or search_stock_media.

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 an explicit when-to-use rule relative to generate_image: 'Reuse one instead of generating a new image when the brief matches.' It also distinguishes the source modes, but offers no when-not guidance or explicit routing against near neighbours such as search_stock_media or list_account_media.

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