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

Annotations already declare readOnlyHint=true and openWorldHint=false, but the description adds auth/cost context ('Free, no key') that the annotations do not express, and confirms the payload is SVG code text. It omits error behavior for an unknown slug, though that is minor for a read-only lookup.

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 short sentences, front-loaded with what is returned before the input source. The telegraphic 'Free, no key.' is slightly clipped but each fragment carries information, so there is little waste.

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 one-parameter, read-only fetch with no output schema or nested objects, the description covers purpose, slug provenance, auth, and return type adequately. Only failure modes for a bad slug are left unaddressed.

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 0% and the single parameter is undocumented in the schema, so the description carries the burden. It does add value by telling the agent where valid slugs come from, but it never states the slug format, case sensitivity, or whether it must be an exact match.

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 the concrete output and resource: the SVG code of a single free library item. It implicitly separates itself from svg_generate/svg_vectorize by identifying the item as coming from the library, but it never names those siblings or explicitly says it does not generate or convert.

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?

Names the prerequisite producer of the input ('slug from svg_library_search'), which is an explicit routing hint for sequencing search-then-get. It gives no exclusion guidance, e.g. when to use this versus svg_generate for a new asset.

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