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

Annotations already declare read-only, open-world, idempotent, and non-destructive behavior. The description adds substantial value beyond these: it enumerates exactly what fields will be returned, including organisational roles (coordinator vs participant), and provides the ID format specifics and browser URL guidance. This gives the agent a clear picture of the tool's output and usage context.

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?

The description is three sentences long, front-loaded with the core purpose and return fields, followed by browser access and ID format guidance. Every sentence contributes unique information with no filler or redundancy, making it both concise and well-structured.

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?

Given the tool has a single parameter, an output schema, and annotations covering safety, the description is fully adequate. It details the input format, what will be returned, and even provides a browser alternative. No critical information for an agent to call the tool correctly is missing; edge cases like invalid IDs are not necessary given the output schema.

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?

The input schema already provides 100% coverage with a detailed description of the grant_id parameter, including examples and where to find it. The description's mention of ID digit lengths merely repeats schema content without adding new meaning. Thus the description does not significantly enhance parameter semantics beyond the schema baseline.

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 description states a specific verb ('Retrieve'), resource ('full details for a specific EU-funded research project'), and identifier ('by its grant agreement number'). It explicitly lists the returned data fields (title, acronym, abstract, dates, funding, etc.), which distinguishes it from sibling CORDIS tools like project_search (which finds projects) and project_publications (which lists publications).

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 description clearly implies that this tool is for retrieving details of a known project, given the requirement of a grant agreement number. It provides guidance on ID formats (9-digit Horizon Europe, 6-digit H2020) and mentions the CORDIS project page for browser access. However, it does not explicitly contrast with siblings (e.g., 'use project_search to find the ID first'), so the decision is left to inference rather than being stated.

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